Intel QX9770 - Core 2 Extreme Quad-Core Processor, QX68000 Core 2 Extreme Design Manual

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Intel® Core™2 Extreme Processor

QX6800 Extreme Processor QX9770

Thermal and Mechanical Design Guidelines

— For the Intel® Core™2 Extreme Processor QX6800Δ B3

Stepping and the Intel® Core™2 Extreme Processor QX9770Δ C0 Stepping

March 2008

and Intel® Core™2

Document Number: 316854-002

LGA775 Socket Heatsink Loading

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Copies of documents which have an order number and are referenced in this document, or other Intel literature, may be obtained by calling 1 -800-548-4725, or by visiting

The Intel errors known as errata, which may cause the product to deviate from published specifications. Current characterized errata are available on request.

Not all specified units of this p rocessor support Thermal Monitor 2 (TM2). See the Processor Spec Finder at http://processorfinder.intel.com or contact your Intel representative for more information.

∆

family, not across differe nt processor families. Over time processor numbers will increment based on changes in clock, speed, cache, FSB, or other features, and increments are not intended to represent proportional or quantitative increases in any particular feature. Current roadmap processor number progression is not necessarily representative of future roadmaps. See www.intel.com/products/processor_number for details.

Intel, Pentium, Core, and the Int el logo are trademarks of Intel Corporation in the U.S. and other countries. *Other names and brands may be claimed as the property of others. Copyright © 2007–2008 Intel Corporation

Core™2 Extreme Processor QX6800 and Intel® Core™2 Extreme Processor QX9770 may contain design defects or

Intel processor numbers are not a measure of performance. Processor numbers differentiate features within each processor

http://www.intel.com .

2 Thermal and Mechanical Design Guidelines

Contents

1 Introduction.....................................................................................................9

1.1 Document Goals and Scope .....................................................................9

1.1.1 Importance of Thermal Management............................................9

1.1.2 Document Goals........................................................................9

1.1.3 Document Scope.....................................................................10

1.2 References..........................................................................................11

1.3 Definition of Terms...............................................................................11

2 Processor Thermal/Mechanical Information.........................................................13

2.1 Mechanical Requirements ......................................................................13

2.1.1 Processor Package ...................................................................13

2.1.2 Heatsink Attach ......................................................................15

2.1.2.1 General Guidelines....................................................15

2.1.2.2 The Pump Assembly Clip Load Requirement..................15

2.1.2.3 Additional Guidelines.................................................16

2.2 Thermal Requirements..........................................................................16

2.2.1 Processor Case Temperature.....................................................16

2.2.2 Thermal Profile .......................................................................17

2.2.3 T

2.3 Heatsink Design Considerations..............................................................19

2.3.1 Heatsink Size..........................................................................20

2.3.2 Package IHS Flatness...............................................................20

2.3.3 Thermal Interface Material........................................................21

2.4 System Thermal Solution Considerations .................................................21

2.4.1 Chassis Thermal Design Capabilities...........................................21

2.4.2 Improving Chassis Thermal Performance ....................................21

2.4.3 Summary...............................................................................22

2.5 System Integration Considerations..........................................................22

..................................................................................18

CONTROL

3 Thermal Metrology..........................................................................................23

3.1 Characterizing Cooling Performance Requirements....................................23

3.1.1 Example ................................................................................25

3.2 Processor Thermal Solution Performance Assessment................................26

3.3 Local Ambient Temperature Measurement Guidelines.................................26

3.4 Processor Case Temperature Measurement Guidelines...............................29

4 Thermal Management Logic and Thermal Monitor Feature.....................................31

4.1 Processor Power Dissipation ...................................................................31

4.2 Thermal Monitor Implementation............................................................31

4.2.1 PROCHOT# Signal...................................................................32

4.2.2 Thermal Control Circuit ............................................................32

4.2.3 Thermal Monitor 2...................................................................33

4.2.4 Operation and Configuration .....................................................34

4.2.5 On-Demand Mode ...................................................................35

4.2.6 System Considerations.............................................................35

4.2.7 Operating System and Application Software Considerations...........36

Thermal and Mechanical Design Guidelines 3

LGA775 Socket Heatsink Loading

4.2.8 THERMTRIP# Signal.................................................................36

4.2.9 Cooling System Failure Warning ................................................36

4.2.10 Digital Thermal Sensor.............................................................37

4.2.11 Platform Environmental Control Interface (PECI)..........................38

5 Intel Thermal/Mechanical Reference Design Information.......................................39

5.1 Validation Results for the ATX Reference Design .......................................39

5.1.1 Heatsink Performance..............................................................40

5.1.2 Acoustics ...............................................................................40

5.1.3 Altitude..................................................................................41

5.1.4 Reference Heatsink Thermal Validation.......................................41

5.1.5 Fan Motor Performance ............................................................42

5.1.6 Pump Motor Performance .........................................................43

5.2 Environmental Reliability Testing............................................................44

5.2.1 Structural Reliability Testing .....................................................44

5.2.1.1 Random Vibration Test Procedure................................44

5.2.1.2 Shock Test Procedure................................................45

5.2.2 Power Cycling.........................................................................46

5.2.3 Reliability Testing....................................................................46

5.2.3.1 Tubing Material Selection...........................................48

5.2.3.2 Reservoir Sizing .......................................................48

5.2.3.3 Reliability Test Results...............................................50

5.2.4 Recommended BIOS/CPU/Memory Test Procedures......................51

5.3 Material and Recycling Requirements ......................................................52

5.4 Safety Requirements ............................................................................52

5.5 Geometric Envelope for Intel Reference ATX Thermal Mechanical Design......52

5.6 Reference Attach Mechanism..................................................................54

5.7 Socket and Voltage Regulation Cooling Strategy .......................................55

6 Intel® Quiet System Technology (Intel® QST) .....................................................57

6.1 Intel® Quiet System Technology Algorithm...............................................57

6.1.1 Output Weighting Matrix ..........................................................58

6.1.2 Proportional-Integral-Derivative (PID)........................................58

6.2 Board and System Implementation of Intel® Quiet System Technology .......60

6.3 Intel® QST Configuration & Tuning..........................................................62

6.4 Fan Hub Thermistor and Intel® QST ........................................................62

Appendix A LGA775 Socket Heatsink Loading ......................................................................63

A.1 LGA775 Socket Heatsink Considerations..................................................63

A.2 Metric for Heatsink Preload for ATX/uATX Designs Non-Compliant with Intel®

Reference Design .................................................................................

A.2.1 Heatsink Preload Requirement Limitations...................................64

A.2.2 Motherboard Deflection Metric Definition.....................................64

A.2.3 Board Deflection Limits ............................................................66

A.2.4 Board Deflection Metric Implementation Example.........................66

A.2.5 Additional Considerations .........................................................67

A.2.5.1 Motherboard Stiffening Considerations.........................68

A.3 Heatsink Selection Guidelines.................................................................68

Appendix B Heatsink Clip Load Metrology............................................................................69

B.1 Overview ............................................................................................69

B.2 Test Preparation...................................................................................69

4 Thermal and Mechanical Design Guidelines

B.2.1 Heatsink Preparation................................................................69

B.2.2 Typical Test Equipment ............................................................72

B.3 Test Procedure Examples.......................................................................72

B.3.1 Time-Zero, Room Temperature Preload Measurement...................73

B.3.2 Preload Degradation under Bake Conditions ................................73

Appendix C Thermal Interface Management.........................................................................75

C.1 Bond Line Management.........................................................................75

C.2 Interface Material Area..........................................................................75

C.3 Interface Material Performance...............................................................75

Appendix D Case Temperature Reference Metrology..............................................................77

D.1 Objective and Scope .............................................................................77

D.2 Supporting Test Equipment....................................................................78

D.3 Thermal Calibration and Controls............................................................79

D.4 IHS Groove .........................................................................................79

D.5 Thermocouple Attach Procedure .............................................................82

D.5.1 Thermocouple Conditioning and Preparation................................82

D.5.2 Thermocouple Attachment to the IHS.........................................83

D.5.3 Solder Process........................................................................88

D.5.4 Cleaning and Completion of Thermocouple Installation..................91

D.6 Thermocouple Wire Management............................................................95

Appendix E Legacy Fan Speed Control................................................................................97

E.1 Thermal Solution Design .......................................................................97

E.1.1 Determine Thermistor Set Points ...............................................97

E.1.2 Minimum Fan Speed Set Point...................................................98

E.2 Board and System Implementation .........................................................99

E.2.1 Choosing Fan Speed Control Settings .........................................99

E.2.1.1 Temperature to Begin Fan Acceleration......................100

E.2.1.2 Minimum PWM Duty Cycle........................................ 102

E.3 Combining Thermistor and Digital Thermal sensor Control........................103

E.4 Interaction of Thermal Profile and T

CONTROL

.............................................103

Appendix F BTX System Thermal Considerations................................................................ 109

Appendix G Mechanical Drawings .....................................................................................113

Appendix H Intel Enabled Reference Solution Information.................................................... 123

Thermal and Mechanical Design Guidelines 5

Figures

LGA775 Socket Heatsink Loading

Figure 1. Package IHS Load Areas.....................................................................13

Figure 2. Processor Case Temperature Measurement Location ...............................17

Figure 3. Example Thermal Profile.....................................................................18

Figure 4. Processor Thermal Characterization Parameter Relationships....................24

Figure 5. Locations for Measuring Local Ambient Temperature, Active Heatsink........27

Figure 6. Locations for Measuring Local Ambient Temperature, Liquid-Cooling Heat

Exchanger.........................................................................................

Figure 7. Locations for Measuring Local Ambient Temperature, Passive Heatsink......28

Figure 8. Concept for Clocks under Thermal Monitor Control..................................33

Figure 9. Thermal Monitor 2 Frequency and Voltage Ordering................................34

Figure 10. T

for Digital Thermometer ........................................................37

CONTROL

Figure 11. Random Vibration PSD......................................................................44

Figure 12. Shock Acceleration Curve..................................................................45

Figure 13. The Assembly Cumulative Mass Loss Data in Continuous Operation

Test at 50 ºC and 1450 RPM..............................................................

Figure 14. Thermal Resistance Curve for Liquid Loss of Reservoir...........................49

Figure 15. Reservoir Location............................................................................50

Figure 16. Intel® ALCT Reference Design Major Components.................................53

Figure 17. Heat Exchanger Fan Combination Foot Print View .................................53

Figure 18. Structure to Motherboard Interface.....................................................54

Figure 19. Diagram of Location of Heat Exchanger VR and Socket Airflow Cooling

Feature...........................................................................................

Figure 20. CPU Maximum Current Draw for Heat Exchanger Fan Speed...................56

Figure 21. Intel® Quiet System Technology Overview...........................................58

Figure 22. PID Controller Fundamentals .............................................................59

Figure 23. Intel® Quiet System Technology Platform Requirements ........................60

Figure 24. Example Acoustic Fan Speed Control Implementation............................61

Figure 25. Digital Thermal Sensor and Thermistor................................................62

Figure 26. Board Deflection Definition................................................................65

Figure 27. Example: Defining Heatsink Preload Meeting Board Deflection Limit ........67

Figure 28. Load Cell Installation in Machined Heatsink Base Pocket – Bottom View ...70

Figure 29. Load Cell Installation in Machined Heatsink Base Pocket – Side View .......71

Figure 30. Preload Test Configuration.................................................................71

Figure 31. Omega Thermocouple.......................................................................79

Figure 32. 775-LAND LGA Package Reference Groove Drawing...............................80

Figure 33. IHS Groove on the 775-LAND LGA Package..........................................81

Figure 34. IHS Groove Orientation Relative to the LGA775 Socket..........................81

Figure 35. Inspection of Insulation on Thermocouple............................................82

Figure 36. Bending the Tip of the Thermocouple..................................................83

Figure 37. Securing Thermocouple Wires with Kapton* Tape Prior to Attach ............83

Figure 38. Thermocouple Bead Placement...........................................................84

Figure 39. Position Bead on the Groove Step.......................................................85

Figure 44. Detailed Thermocouple Bead Placement ..............................................85

Figure 41. Third Tape Installation......................................................................86

Figure 42. Measuring Resistance between Thermocouple and IHS ..........................86

Figure 43. Applying Flux to the Thermocouple Bead.............................................87

Figure 44. Cutting Solder.................................................................................87

Figure 45. Positioning Solder on IHS..................................................................88

Figure 46. Solder Station Setup ........................................................................89

Figure 47. View Through Lens at Solder Station...................................................90

Figure 48. Moving Solder back onto Thermocouple Bead.......................................90

6 Thermal and Mechanical Design Guidelines

Figure 49. Removing Excess Solder ...................................................................91

Figure 50. Thermocouple placed into groove.......................................................92

Figure 51. Removing Excess Solder ...................................................................92

Figure 52. Filling Groove with Adhesive..............................................................93

Figure 53. Application of Accelerant...................................................................93

Figure 54. Removing Excess Adhesive from IHS ..................................................94

Figure 55. Finished Thermocouple Installation.....................................................94

Figure 56. Thermocouple Wire Management........................................................95

Figure 57. Thermistor Set Points .......................................................................98

Figure 58. Example Fan Speed Control Implementation........................................99

Figure 59. Fan Speed Control..........................................................................100

Figure 60. Temperature Range = 5 °C ............................................................. 101

Figure 61. Temperature Range = 10 °C............................................................ 102

Figure 62. Digital Thermal Sensor and Thermistor..............................................103

Figure 63. FSC Definition Example................................................................... 105

Figure 64. System Airflow Illustration with System Monitor Point Area Identified.... 110

Figure 65. Thermal sensor Location Illustration ................................................. 111

Figure 66. ATX/µATX Motherboard Keep-out Footprint Definition and Height

Restrictions for Enabling Components - Sheet 1..................................

114

Figure 67. ATX/µATX Motherboard Keep-out Footprint Definition and Height

Restrictions for Enabling Components - Sheet 2..................................

115

Figure 68. ATX/µATX Motherboard Keep-out Footprint Definition and Height

Restrictions for Enabling Components - Sheet 3..................................

116

Figure 69. Balanced Technology Extended (BTX) Thermal Module Keep Out

Volumetric – Sheet 1......................................................................

117

Figure 70. Balanced Technology Extended (BTX) Thermal Module Keep Out

Volumetric – Sheet 2......................................................................

118

Figure 71. Balanced Technology Extended (BTX) Thermal Module Keep Out

Volumetric – Sheet 3......................................................................

119

Figure 72. Balanced Technology Extended (BTX) Thermal Module Keep Out

Volumetric – Sheet 4......................................................................

120

Figure 73. Balanced Technology Extended (BTX) Thermal Module Keep Out

Volumetric – Sheet 5......................................................................

121

Figure 74. Intel Advanced Liquid Cooling Technology Assembly............................122

Tables

Table 1. Heatsink Inlet Temperature of Intel Reference Thermal Solutions..............21

Table 2. Intel Liquid Cooled Reference Design Performance (ALCT).........................40

Table 3. Acoustic Results.................................................................................. 40

Table 4. Fan Electrical Performance Requirements ...............................................42

Table 5. Pump Electrical Performance Requirements.............................................43

Table 6. The Reliability Test Matrix ....................................................................47

Table 7. The Weekly Loss Rate of Different Tubing Materials..................................48

Table 8. Reliability Test Results.........................................................................51

Table 9. Maximum Estimated Processor Current Capability at 35 ºC External

Ambient.............................................................................................

Table 10. Board Deflection Configuration Definitions ............................................65

Table 11. Typical Test Equipment......................................................................72

Table 12. FSC Definitions...............................................................................104

Table 13. ATX FSC Settings............................................................................106

Table 14. BTX Fan Speed Control Settings........................................................106

Table 15. Intel Representative Contact for Licensing Information ......................... 123

Table 16. Intel Reference Component ATX Thermal Solution Providers.................. 123

Thermal and Mechanical Design Guidelines 7

LGA775 Socket Heatsink Loading

Revision History

Revision

Number

-001 • Initial release April 2007

-002 • Added Intel® Core™2 Extreme processor QX9770 C0 Stepping

• Edits throughout

Description Revision Date

March 2008

8 Thermal and Mechanical Design Guidelines

Introduction

1 Introduction

1.1 Document Goals and Scope

1.1.1 Importance of Thermal Management

The objective of thermal management is to ensure that the temperatures of all components in a system are maintained within their functional temperature range. Within this temperature range, a component is expected to meet its specified performance. Operation outside the functional temperature range can degrade system performance, cause logic errors or cause component and/or system damage. Temperatures exceeding the maximum operating limit of a component may result in irreversible changes in the operating characteristics of this component.

In a system environment, the processor temperature is a function of both system and component thermal characteristics. The system level thermal constraints consist of the local ambient air temperature and airflow over the processor as well as the physical constraints at and above the processor. The processor temperature depends in particular on the component power dissipation, the processor package thermal characteristics, and the processor thermal solution.

All of these parameters are affected by the continued push of technology to increase processor performance levels and packaging density (more transistors). As operating frequencies increase and packaging size decreases, the power density increases while the thermal solution space and airflow typically become more constrained or remains the same within the system. The result is an increased importance on system design to ensure that thermal design requirements are met for each component, including the processor, in the system.

1.1.2 Document Goals

Depending on the type of system and the chassis characteristics, new system and component designs may be required to provide adequate cooling for the processor. The goal of this document is to provide an understanding of these thermal characteristics and discuss guidelines for meeting the thermal requirements imposed on single processor systems using the Intel Stepping and Intel

The concepts given in this document are applicable to any system form factor. Specific examples used will be the Intel enabled reference solution for ATX/uATX systems. See the applicable BTX form factor reference documents to design a thermal solution for that form factor.

Core™2 Extreme processor QX9770 C0 Stepping.

Core™2 Extreme processor QX6800 B3

Thermal and Mechanical Design Guidelines 9

1.1.3 Document Scope

This design guide supports the following processor:

• Intel® Core™2 Extreme processor QX6800 B3 Stepping

• Intel® Core™2 Extreme processor QX9770 C0 Stepping

In this document when a reference is made to “the processor” it is intended that this includes all the processors supported by this document. If needed for clarity, the specific processor will be listed.

LGA775 Socket Heatsink Loading

In this document, when a reference is made to “the datasheet”, the reader should refer to the Intel

Processor Q9000 Series Datasheet and Intel QX6000

Sequence and Intel® Core™2 Quad Processor Q6000Δ Sequence Datasheet,

Core™2 Extreme Processor QX9000 Series and Intel® Core™2 Quad

Core™2 Extreme Quad-Core Processor

as appropriate. If needed for clarity the specific processor datasheet will be referenced.

Chapter

2 of this document discusses package thermal mechanical requirements to

design a thermal solution for the processor in the context of personal computer applications. Chapter

3 discusses the thermal solution considerations and metrology

recommendations to validate a processor thermal solution. Chapter

4 addresses the benefits of the processor’s integrated thermal management

logic for thermal design. Chapter

Advanced Liquid Cooling Technology) for the processor. Chapter 6 discusses the implementation of Intel

5 gives information on the Intel reference thermal solution called ALCT (Intel

Quiet System Technology.

The physical dimensions and thermal specifications of the processor that are used in this document are for illustration only. Refer to the datasheet for the product dimensions, thermal power dissipation and maximum case temperature. In case of conflict, the data in the datasheet supersedes any data in this document.

10 Thermal and Mechanical Design Guidelines

Introduction

1.2 References

Material and concepts available in the following documents may be beneficial when reading this document.

Document Location

Intel® Core™2 Extreme Processor QX9000 Series and Intel® Core™2 Quad Processor Q9000 Series Datasheet

Intel® Core™2 Extreme Quad-Core Processor QX6000Δ Sequence and Intel Datasheet

LGA775 Socket Mechanical Design Guide

Fan Specification for 4-wire PWM Controlled Fans http://www.formfactors.org/ ATX Thermal Design Suggestions http://www.formfactors.org/ microATX Thermal Design Suggestions http://www.formfactors.org/ Balanced Technology Extended (BTX) System Design Guide http://www.formfactors.org/

Core™2 Quad Processor Q6000Δ Sequence

1.3 Definition of Terms

Term Description

The measured ambient temperature locally surrounding the processor. The ambient

C-MAX

LIQUID

temperature should be measured just upstream of a passive heatsink or at the fan inlet for an active heatsink.

The case temperature of the processor, measured at the geometric center of the topside of the IHS.

The ambient air temperature external to a system chassis. This temperature is usually measured at the chassis air inlets.

Heatsink temperature measured on the underside of the heatsink base, at a location corresponding to

The maximum case temperature as specified in a component specification.

Working fluid temperature as it leaves the pump (or enters the heat exchanger).

Case-to-ambient thermal characterization parameter (psi). A measure of thermal solution performance using total package power. Defined as (T Power.

Note: Heat source must be specified for Case-to-sink thermal characterization parameter. A measure of thermal interface

material performance using total package power. Defined as (T Power.

Note: Heat source must be specified for Sink-to-ambient thermal characterization parameter. A measure of heatsink thermal

performance using total package power. Defined as (T Note: Heat source must be specified for

http://w.ww.intel.com/design/pro

cessor/datashts/318726.htm

http://developer.intel.com/design

/processor/datashts/315592.htm

http://intel.com/design/

Pentium4/guides/ 302666.htm

– TA) / Total Package

Ψ measurements.

– TS) / Total Package

Ψ measurements.

– TA) / Total Package Power.

Ψ measurements.

Thermal and Mechanical Design Guidelines 11

LGA775 Socket Heatsink Loading

Term Description

Thermal Interface Material: The thermally conductive compound between the heatsink

TIM

and the processor case. This material fills the air gaps and voids, and enhances the transfer of the heat from the processor case to the heatsink.

MAX

TDP

IHS

LGA775 Socket

The maximum power dissipated by a semiconductor component.

Thermal Design Power: a power dissipation target based on worst-case applications. Thermal solutions should be designed to dissipate the thermal design power.

Integrated Heat Spreader: a thermally conductive lid integrated into a processor package to improve heat transfer to a thermal solution through heat spreading.

The surface mount socket designed to accept the processors in the 775–Land LGA package.

ACPI

Bypass

Thermal

Monitor

TCC

DTS

DIODE

FSC

CONTROL_BASE

CONTROL_OFFSET

CONTROL

PWM

Health Monitor

Component

BTX

TMA

Advanced Configuration and Power Interface. Bypass is the area between a passive heatsink and any object that can act to form a

duct. For this example, it can be expressed as a dimension away from the outside dimension of the fins to the nearest surface.

A feature on the processor that attempts to keep the processor die temperature within factory specifications.

Thermal Control Circuit: Thermal Monitor uses the TCC to reduce die temperature by lowering effective processor frequency when the die temperature has exceeded its operating limits.

Digital Thermal Sensor: Processor die sensor temperature defined as an offset from the onset of PROCHOT#.

Temperature reported from the on-die thermal diode. Fan Speed Control: Thermal solution that includes a variable fan speed which is

driven by a PWM signal and uses the digital thermal sensor as a reference to change the duty cycle of the PWM signal.

Constant from the processor datasheet that is added to the T results in the value for

CONTROL

CONTROL_OFFSET

Value read by the BIOS from a processor MSR and added to the T results in the value for

is the specification limit for use with the digital thermal sensor.

CONTROL

CONTROL_BASE

that

Pulse width modulation is a method of controlling a variable speed fan. The enabled 4 wire fans use the PWM duty cycle % from the fan speed controller to modulate the fan speed.

Any standalone or integrated component that is capable of reading the processor temperature and providing the PWM signal to the 4 pin fan header.

Balanced Technology Extended Thermal Module Assembly. The heatsink, fan and duct assembly for the BTX thermal

solution

12 Thermal and Mechanical Design Guidelines

Processor Thermal/Mechanical Information

2 Processor Thermal/Mechanical

Information

2.1 Mechanical Requirements

2.1.1 Processor Package

The processors covered in the document are packaged in a 775-Land LGA package that interfaces with the motherboard via a LGA775 socket. Refer to the datasheet for detailed mechanical specifications.

The processor connects to the motherboard through a land grid array (LGA) surface mount socket. The socket contains 775 contacts arrayed about a cavity in the center of the socket with solder balls for surface mounting to the motherboard. The socket is named LGA775 socket. A description of the socket can be found in the LGA775 Socket Mechanical Design Guide.

The package includes an integrated heat spreader (IHS) that is shown in illustration only. Refer to the processor datasheet for further information. In case of conflict, the package dimensions in the processor datasheet supersedes dimensions provided in this document.

Figure 1. Package IHS Load Areas

Top Surface of IHS

Substrate

Top Surface of IHS

to install a heatsink

Figure 1 for

IHS Step

to interface with LGA775

Socket Load Plate

Thermal and Mechanical Design Guidelines 13

LGA775 Socket Heatsink Loading

The primary function of the IHS is to transfer the non-uniform heat distribution from the die to the top of the IHS, out of which the heat flux is more uniform and spread over a larger surface area (not the entire IHS area). This allows more efficient heat transfer out of the package to an attached cooling device. The top surface of the IHS is designed to be the interface for contacting a heatsink.

The IHS also features a step that interfaces with the LGA775 socket load plate, as described in LGA775 Socket Mechanical Design Guide. The load from the load plate is distributed across two sides of the package onto a step on each side of the IHS. It is then distributed by the package across all of the contacts. When correctly actuated, the top surface of the IHS is above the load plate allowing proper installation of a heatsink on the top surface of the IHS. After actuation of the socket load plate, the seating plane of the package is flush with the seating plane of the socket. Package movement during socket actuation is along the Z direction (perpendicular to substrate) only. Refer to the LGA775 Socket Mechanical Design Guide for further information about the LGA775 socket.

The processor package has mechanical load limits that are specified in the processor datasheet. The specified maximum static and dynamic load limits should not be exceeded during their respective stress conditions. These include heatsink installation, removal, mechanical stress testing, and standard shipping conditions.

• When a compressive static load is necessary to ensure thermal performance of the thermal interface material between the heatsink base and the IHS, it should not exceed the corresponding specification given in the processor datasheet.

• When a compressive static load is necessary to ensure mechanical performance, it should remain in the minimum/maximum range specified in the processor datasheet

• The heatsink mass can also generate additional dynamic compressive load to the package during a mechanical shock event. Amplification factors due to the impact force during shock must be taken into account in dynamic load calculations. The total combination of dynamic and static compressive load should not exceed the processor datasheet compressive dynamic load specification during a vertical shock. For example, with a 0.550 kg [1.2 lb] heatsink, an acceleration of 50G during an 11 ms trapezoidal shock with an amplification factor of 2 results in approximately a 539 N [117 lbf] dynamic load on the processor package. If a 178 N [40 lbf] static load is also applied on the heatsink for thermal performance of the thermal interface material the processor package could see up to a 717 N [156 lbf]. The calculation for the thermal solution of interest should be compared to the processor datasheet specification.

No portion of the substrate should be used as a load- bearing surface. Finally, the processor datasheet provides package handling guidelines in terms of

maximum recommended shear, tensile and torque loads for the processor IHS relative to a fixed substrate. These recommendations should be followed in particular for heatsink removal operations.

14 Thermal and Mechanical Design Guidelines

Processor Thermal/Mechanical Information

2.1.2 Heatsink Attach

2.1.2.1 General Guidelines

There are no features on the LGA775 socket to directly attach a heatsink: a mechanism must be designed to attach the heatsink directly to the motherboard. In addition to holding the heatsink in place on top of the IHS, this mechanism plays a significant role in the robustness of the system in which it is implemented, in particular:

• Ensuring thermal performance of the thermal interface material (TIM) applied between the IHS and the heatsink. TIMs based on phase change materials are very sensitive to applied pressure: the higher the pressure, the better the initial performance. TIMs, such as thermal greases, are not as sensitive to applied pressure. Designs should consider a possible decrease in applied pressure over time due to potential structural relaxation in retention components.

• Ensuring system electrical, thermal, and structural integrity under shock and vibration events. The mechanical requirements of the heatsink attach mechanism depend on the mass of the heatsink and the level of shock and vibration that the system must support. The overall structural design of the motherboard and the system have to be considered when designing the heatsink attach mechanism. Their design should provide a means for protecting LGA775 socket solder joints. The Intel ALCT reference design attach mechanism described in Section.

5.6

Note: Package pull-out during mechanical shock and vibration i s constrained by the LGA775

socket load plate (refer to the LGA775 Socket Mechanical Design Guide for further information).

2.1.2.2 The Pump Assembly Clip Load Requirement

The attach mechanism for the pump assembly developed to support the processor should create a static preload on the package between 18 lbf and 70 lbf throughout the life of the product for designs compliant with the Intel reference design assumptions:

• 72 mm x 72 mm mounting hole span (refer to

The minimum load is required to protect against fatigue failure of socket solder joint in temperature cycling.

It is important to take into account potential load degradation from creep over time when designing the pump assembly clip to the required minimum load. This means the initial preload at beginning of life of the product may be significantly higher than the minimum preload that must be met throughout the life of the product. For additional guidelines on mechanical design, in particular on designs departing from the reference design assumptions, refer to

For clip load metrology guidelines, refer to

Appendix A.

Appendix B.

Figure 66)

Thermal and Mechanical Design Guidelines 15

2.1.2.3 Additional Guidelines

In addition to the general guidelines given above, the heatsink attach mechanism for the processor should be designed to the following guidelines:

• Holds the heatsink in place under mechanical shock and vibration events and applies force to the heatsink base to maintain desired pressure on the thermal interface material. Note that the load applied by the heatsink attach mechanism

must comply with the package specifications described in the processor datasheet. One of the key design parameters is the height of the top surface of the processor IHS above the motherboard. The IHS height from the top of board is expected to vary from 7.517 mm to 8.167 mm. This data is provided for information only, and should be derived from:

⎯ The height of the socket seating plane above the motherboard after reflow,

given in the LGA775 Socket Mechanical Design Guide with its tolerances

⎯ The height of the package, from the package seating plane to the top of the

IHS, and accounting for its nominal variation and tolerances that are given in the corresponding processor datasheet.

• Engages easily, and if possible, without the use of special tools. In general, the heatsink is assumed to be installed after the motherboard has been installed into the chassis.

• Minimizes contact with the motherboard surface during installation and actuation to avoid scratching the motherboard.

LGA775 Socket Heatsink Loading

2.2 Thermal Requirements

Refer to the datasheet for the processor thermal specifications. The majority of processor power is dissipated through the IHS. There are no additional components, e.g., BSRAMs, which generate heat on this package. The amount of power that can be dissipated as heat through the processor package substrate and into the socket is usually minimal.

The thermal limits for the processor are the Thermal Profile and T Profile defines the maximum case temperature as a function of power being dissipated. T

CONTROL

reported by the digital thermal sensor and a fan speed control method. Designing to these specifications allows optimization of thermal designs for processor performance and acoustic noise reduction.

2.2.1 Processor Case Temperature

For the processor, the case temperature is defined as the temperature measured at the geometric center of the package on the surface of the IHS. For illustration, Figure 2 shows the measurement location for a 37.5 mm x 37.5 mm [1.474 in x 1.474 in] 775-Land LGA processor package with a 28.7 mm x 28.7 mm [1.13 in x 1.13 in] IHS top surface. Techniques for measuring the case temperature are detailed in Section

Note: In case of conflict, the package dimensions in the processor datasheet supersedes

dimensions provided in this document.

3.4.

is a specification used in conjunction with the temperature

. The Thermal

CONTROL

16 Thermal and Mechanical Design Guidelines

Processor Thermal/Mechanical Information

Figure 2. Processor Case Temperature Measurement Location

37.5 mm

2.2.2 Thermal Profile

The Thermal Profile defines the maximum case temperature as a function of processor power dissipation. Refer to the datasheet for the further information.

While the thermal profile provides flexibility for ATX /BTX thermal design based on its intended target thermal environment, thermal solutions that are intended to function in a multitude of systems and environments need to be designed for the worst-case thermal environment. The majority of ATX /BTX platforms are targeted to function in an environment that will have up to a 35 °C ambient temperature external to the system.

For ATX platforms using the Intel and QX9770 C0 stepping, an active liquid-cooled design should be designed to manage the heat exchanger inlet temperature of 35 ºC + 3 ºC = 38 ºC (see Chapter

5).

Measure TCat this point

(geo metric center of the package)

37.5 mm

Core™2 Extreme processor QX6800 B3 stepping

For BTX platforms, the similar BTX liquid cooling design should be designed to manage the heat exchanger inlet temperature of 35 ºC + 0.5 ºC = 35.5 ºC.

The slope of the thermal profile was established to be the same as the Intel liquid cooling solution thermal solution performance. This performance is expressed as the slope on the thermal profile and can be thought of as the thermal resistance of the heatsink attached to the processor, Ψ

(Refer to Section 3.1). The intercept on the

thermal profile assumes a maximum ambient operating condition that is consistent with the available chassis solutions.

The thermal profiles for the processor are defined such that a single thermal solution (e.g., ALCT reference design) can be used for Intel QX6800 B3 Stepping and QX9770 C0 Stepping processors. See Chapter

Core™2 Extreme processor

5 for a

discussion of the ALCT reference design. To determine compliance to the thermal profile, a measurement of the actual processor power dissipation is required. The measured power is plotted on the Thermal Profile to determine the maximum case

Thermal and Mechanical Design Guidelines 17

temperature. Using the example in Figure 3 for a processor dissipating 110W the maximum case temperature is 52.2°C. See the datasheet for the thermal profile.

Figure 3. Example Thermal Profile

LGA775 Socket Heatsink Loading

2.2.3 T

T when the thermal solution fan speed is being controlled by the digital thermal sensor.

The T speed can be reduced. This allows the system integrator a method to reduce the

acoustic noise of the processor cooling solution, while maintaining compliance to the processor thermal specification.

Note: The T

activation set point which will be seen as 0 via the digital thermometer. As a result the T the thermal management logic and features and Chapter 6 on Intel® Quiet System

Technology (Intel

The value of T of these is the processor idle power. As a result a processor with a high (closer to 0)

T more negative number) of T

The value of T T some parts is offset by a higher value of T behave similarly in the acoustic performance.

CONTROL

defines the maximum operating temperature for the digital thermal sensor

parameter defines a very specific processor operating region where fan

value for the processor is relative to the Thermal Control Circuit (TCC)

value will always be a negative number. See Chapter 4 for the discussion

QST).

CONTROL

will dissipate more power than a part with lower value (farther from 0, e.g.

CONTROL

value the thermal solution should perform similarly. The higher power of

is driven by a number of factors. One of the most significant

CONTROL

when running the same application.

is calculated such that regardless of the individual processor’s

CONTROL

in such a way that they should

18 Thermal and Mechanical Design Guidelines

Processor Thermal/Mechanical Information

This is achieved in part by using the ΨCA vs. RPM and RPM vs. Acoustics (dBA) performance curves from the Intel enabled thermal solution. A thermal solution

designed to meet the thermal profile would be expected to provide similar acoustic performance of different parts with potentially different T

The value for T

CONTROL

is calculated by the system BIOS based on values read from a

factory configured processor register. The result can be used to program a fan speed control component. See the processor datasheet for further details on reading the register and calculating T

See Chapter

6 Intel

CONTROL

Quiet System Technology (Intel® QST) for details on

implementing a design using T

and the Thermal Profile.

CONTROL

2.3 Heatsink Design Considerations

To remove the heat from the processor, three basic parameters should be considered:

The area of the surface on which the heat transfer takes place. Without

•

any enhancements, this is the surface of the processor package IHS. One method used to improve thermal performance is by attaching a heatsink to the IHS. A heatsink can increase the effective heat transfer surface area by conducting heat out of the IHS and into the surrounding air through fins attached to the heatsink base.

The conduction path from the heat source to the heatsink fins. Providing a

•

direct conduction path from the heat source to the heatsink fins and selecting materials with higher thermal conductivity typically improves heatsi nk performance. The length, thickness, and conductivity of the conduction path from the heat source to the fins directly impact the thermal performance of the heatsink. In particular, the quality of the contact between the package IHS and the heatsink base has a higher impact on the overall thermal solution performance as processor cooling requirements become stricter. Thermal interface material (TIM) is used to fill in the gap between the IHS and the bottom surface of the heatsink, and thereby improve the overall performance of the stack-up (IHS-TIMHeatsink). With extremely poor heatsink interface flatness or roughness, TIM may not adequately fill the gap. The TIM thermal performance depends on its thermal conductivity as well as the pressure applied to it. Refer to Section

Appendix C for further information on TIM and on bond line management between

the IHS and the heatsink base.

The heat transfer conditions on the surface on which heat transfer takes

•

place. Convective heat transfer occurs between the airflow and the surface exposed to the flow. It is characterized by the local ambient temperature of the

, and the local air velocity over the surface. The higher the air velocity over

air, T

the surface, and the cooler the air, the more efficient is the resulting cooling. The nature of the airflow can also enhance heat transfer via convection. Turbulent flow can provide improvement over laminar flow. In the case of a heatsink, the surface exposed to the flow includes in particular the fin faces and the heatsink base.

CONTROL

values.

2.3.3 and

Liquid Cooling Technology typically incorporates a fan, an integrated pump with cold plate and an air radiator type heat exchanger. The design takes advantage of a pump to provide a uniform liquid-flow across the cold plate taking away the heat then go to the exchanger. Finally, a fan manages the airflow through the exchanger.

Active heatsinks typically incorporate a fan that helps manage the airflow through the heatsink.

Thermal and Mechanical Design Guidelines 19

Passive heatsink solutions require in-depth knowledge of the airflow in the chassis. Typically, passive heatsinks see lower air speed. These heatsinks are therefore typically larger (and heavier) than active heatsinks due to the increase in fin surface required to meet a required performance. As the heatsink fin density (the number of fins in a given cross-section) increases, the resistance to the airflow increases: it is more likely that the air travels around the heatsink instead of through it, unless air bypass is carefully managed. Using air-ducting techniques to manage bypass area can be an effective method for controlling airflow through the heatsink.

2.3.1 Heatsink Size

The size of the heatsink is dictated by height restrictions for installation in a system and by the real estate available on the motherboard and other considerations for component height and placement in the area potentially impacted by the processor heatsink. The height of the heatsink must comply with the requirements and recommendations published for the motherboard form factor of interest. Designing a heatsink to the recommendations may preclude using it in system adhering strictly to the form factor requirements, while still in compliance with the form factor documentation.

For the ATX/microATX form factor, it is recommended to use:

The ATX motherboard keep-out footprint definition and height restrictions for

•

enabling components, defined for the platforms designed with the LGA775 socket in Appendix G of this design guide.

LGA775 Socket Heatsink Loading

The motherboard primary side height constraints defined in the ATX Specification

•

V2.2 and the microATX Motherboard Interface Specification V1.2 found at

http://www.formfactors.org/.

The resulting space available above the motherboard is generally not entirely available for the heatsink. The target height of the heatsink must take into account airflow considerations (for fan performance for example) as well as other design considerations (air duct, etc.).

For BTX form factor, it is recommended to use:

The BTX motherboard keep-out footprint definitions and height restrictions for

•

enabling components for platforms designed with the LGA77 socket in of this design guide.

•

An overview of other BTX system considerations for thermal solutions can be

obtained in the Balanced Technology Extended (BTX) System Design Guide v1.0 found at

http://www.formfactors.org/.

2.3.2 Package IHS Flatness

The package IHS flatness for the product is specified in the datasheet and can be used as a baseline to predict heatsink performance during the design phase.

Intel recommends testing and validating heatsink performance in full mechanical enabling configuration to capture any impact of IHS flatness change due to combined socket and heatsink loading. While socket loading alone may increase the IHS warpage, the heatsink preload redistributes the load on the package and improves the resulting IHS flatness in the enabled state.

Appendix G

20 Thermal and Mechanical Design Guidelines

Processor Thermal/Mechanical Information

2.3.3 Thermal Interface Material

Thermal interface material application between the processor IHS and the heatsink base is generally required to improve thermal conduction from the IHS to the heatsink. Many thermal interface materials can be pre-applied to the heatsink base prior to shipment from the heatsink supplier and allow direct heatsink attach, without the need for a separate thermal interface material dispense or attach process in the final assembly factory.

All thermal interface materials should be sized and positioned on the heatsink base in a way that ensures the entire processor IHS area is covered. It is important to compensate for heatsink-to-processor attach positional alignment when selecting the proper thermal interface material size.

When pre-applied material is used, it is recommended to have a protective application tape over it. This tape must be removed prior to heatsink installation.

2.4 System Thermal Solution Considerations

2.4.1 Chassis Thermal Design Capabilities

The Intel liquid cooling thermal solution assumes that chassis delivers a maximum TA at the inlet of the processor heat exchanger (refer to Section the T

requirements for the ALCT and the similar BTX solutions.

Table 1. Heatsink Inlet Temperature of Intel Reference Thermal Solutions

Topic ATX ALCT BTX Liquid Cooling

Heatsink Inlet Temperature

38 °C 35.5 °C

5.1.1). Table 1 shows

2.4.2 Improving Chassis Thermal Performance

The heat generated by components within the chassis must be removed to provide an adequate operating environment for both the processor and other system components. Moving air through the chassis brings in air from the external ambient environment and transports the heat generated by the processor and other system components out of the system. The number, size and relative position of fans and vents determine the chassis thermal performance, and the resulting ambient temperature around the processor. The size and type (passive or active) of the thermal solution and the amount of system airflow can be traded off against each other to meet specific system design constraints. Additional constraints are board layout, spacing, component placement, acoustic requirements and structural considerations that limit the thermal solution size. For more information, refer to the

ATX Thermal Design Suggestions or microATX Thermal Design Suggestions or Balanced Technology Extended (BTX) System Design Guide v1.0 documents available

on the http://www.formfactors.org/ In addition to passive heatsinks, fan heatsinks and system fans are other solutions

that exist for cooling integrated circuit devices. For example, ducted blowers, heat

web site.

Thermal and Mechanical Design Guidelines 21

pipes and liquid cooling are all capable of dissipating additional heat. Due to their varying attributes, each of these solutions may be appropriate for a particular system implementation.

To develop a reliable, cost-effective thermal solution, thermal characterization and simulation should be carried out at the entire system level, accounting for the thermal requirements of each component. In addition, acoustic noise constraints may limit the size, number, placement, and types of fans that can be used in a particular design.

To ease the burden on thermal solutions, the Thermal Monitor feature and associated logic have been integrated into the silicon of the processor. By taking advantage of the Thermal Monitor feature, system designers may reduce thermal solution cost by designing to TDP instead of maximum power. Thermal Monitor attempts to protect the processor during sustained workload above TDP. Implementation options and recommendations are described in Chapter

2.4.3 Summary

In summary, considerations in heatsink design include:

• The local ambient temperature TA at the heatsink, which is a function of chassis

design.

• The thermal design power (TDP) of the processor, and the corresponding

maximum T combined in a single lump cooling performance parameter, Ψ thermal characterization parameter). More information on the definition and the use of Ψ

• Heatsink i nterface to IHS surface characteristics, including flatness and roughness.

•

The performance of the thermal in terface material used between the heatsink and

the IHS.

• The required heatsi nk clip static load, between 18 lbf to 70 lbf throughout the life

of the product (Refer to Section

• Surface area of the heatsink.

•

Heatsink material and technology.

•

Volume of airflow over the heatsink surface area.

•

Development of airflow entering and within the heatsink area.

•

Physical volumetric constraints placed by the system

LGA775 Socket Heatsink Loading

as calculated from the thermal profile. These parameters are usually

(case to air

is given section 3.1

2.1.2.2 for further information).

2.5 System Integration Considerations

Manufacturing with Intel® Components using 775–Land LGA Package and LGA775 Socket documentation provides Best Known Methods for all aspects LGA775 socket

based platforms and systems manufacturing. Of particular interest for package and heatsink installation and removal is the System Assembly module. A video covering system integration is also available. Contact your Intel field sales representative for further information.

22 Thermal and Mechanical Design Guidelines

Thermal Metrology

3 Thermal Metrology

This section discusses guidelines for testing thermal solutions, including measuring processor temperatures. In all cases, the thermal engineer must measure power dissipation and temperature to validate a thermal solution. To define the performance of a thermal solution the “thermal characterization parameter”, Ψ

3.1 Characterizing Cooling Performance Requirements

The idea of a “thermal characterization parameter”, Ψ (“psi”), is a convenient way to characterize the performance needed for the thermal solution and to compare thermal solutions in identical si tuations (same heat source and local ambient conditions). The thermal characterization parameter is calculated using total package power.

(“psi”) will be used.

Note: Heat transfer is a three-dimensional phenomenon that can rarely be accurately and

easily modeled by a single resistance parameter like Ψ. The case-to-local ambient thermal characterization parameter value (Ψ

measure of the thermal performance of the overall thermal solution that is attached to the processor package. It is defined by the following equation, and measured in units of °C/W:

= (TC – TA) / PD (Equation 1)

Where:

= Case-to-local ambient thermal characterization parameter (°C/W)

= Processor case temperature (°C)

TA = Local ambient temperature in chassis at processor (°C) P

= Processor total power dissipation (W) (assumes all power dissipates

through the IHS)

) is used as a

Thermal and Mechanical Design Guidelines 23

LGA775 Socket Heatsink Loading

The case-to-local ambient thermal characterization parameter of the processor, ΨCA, is comprised of Ψ and of Ψ

Where:

is strongly dependent on the thermal conductivity and thickness of the TIM

between the heatsink and IHS.

is a measure of the thermal characterization parameter from the bottom of the

heatsink to the local ambient air. Ψ conductivity, and geometry. It is also strongly dependent on the air velocity through the fins of the heatsink.

, the sink-to-local ambient thermal characterization parameter:

= ΨCS + ΨSA (Equation 2)

= Thermal characterization parameter of the thermal interface material

= Thermal characterization parameter from heatsink-to-local ambient

, the thermal interface material thermal characterization parameter,

(°C/W)

is dependent on the heatsink material, thermal

Figure 4 illustrates the combination of the different thermal characterization parameters.

Figure 4. Processor Thermal Characterization Parameter Relationships

Heatsink

S C

System Board

TIM

Processor

IHS

LGA775 Socket

24 Thermal and Mechanical Design Guidelines

Thermal Metrology

3.1.1 Example

The cooling performance, Ψ

is then defined using the principle of thermal

CA,

characterization parameter described above:

•

The case temperature T

and thermal design power TDP given in the processor

C-MAX

datasheet.

Define a target local ambient temperature at the processor, T

•

Since the processor thermal profile applies to all processor frequencies, it is important to identify the worst case (lowest Ψ

) for a targeted chassis characterized by TA to

establish a design strategy. The following provides an illustration of how one might determine the appropriate

performance targets. The example power and temperature numbers used here are not related to any specific Intel processor thermal specifications, and are for illustrative purposes only.

Assume the TDP, as listed in the datasheet, is 100W and the maximum case temperature from the thermal profile for 100W is 67 °C. Assume as well that the system airflow has been designed such that the local ambient temperature is 38°C. Then the following could be calculated using equation 1 from above:

= (TC,– TA) / TDP = (67 – 38) / 100 = 0.29 °C/W

To determine the required heatsink performance, a heatsink solution provider would need to determine Ψ

performance for the selected TIM and mechanical load

configuration. If the heatsink solution were designed to work with a TIM material performing at Ψ

≤ 0.10 °C/W, solving for equation 2 from above, the performance of

the heatsink would be:

= ΨCA − ΨCS = 0.29 − 0.10 = 0.19 °C/W

Thermal and Mechanical Design Guidelines 25

LGA775 Socket Heatsink Loading

3.2 Processor Thermal Solution Performance Assessment

Thermal performance of a heatsink should be assessed using a thermal test vehicle (TTV) provided by Intel. The TTV is a stable heat source that the user can make accurate power measurement, whereas processors can introduce additional factors that can impact test results. In particular, the power level from actual processors varies significantly, even when running the maximum power application provided by Intel, due to variances in the manufacturing process. The TTV provides consistent power and power density for thermal solution characterization and results can be easily translated to real processor performance. Accurate measurement of the power dissipated by an actual processor is beyond the scope of this document.

Once the thermal solution is designed and validated with the TTV, it is strongly recommended to verify functionality of the thermal solution on real processors and on fully integrated systems. The Intel maximum power application enables steady power dissipation on a processor to assist in this testing.

3.3 Local Ambient Temperature Measurement Guidelines

The local ambient temperature TA is the temperature of the ambient air surrounding the processor. For a passive heatsink, T temperature; for an actively cooled heatsink, it is the temperature of inlet air to the active cooling fan; for a liquid cooled solution it is the temperature of the air entering the heat exchanger.

It is worthwhile to determine the local ambient temperature in the chassis around the processor to understand the effect it may have on the case temperature.

is best measured by averaging temperature measurements at multiple locations in

the heatsink or heat exchanger inlet airflow. This method helps reduce error and eliminate minor spatial variations in temperature. The following guidelines are meant to enable accurate determination of the localized air temperature around the processor during system thermal testing.

For active heatsinks and liquid cooled solutions, it is important to avoid taking measurement in the dead flow zone that usually develops above the fan hub and hub spokes. Measurements should be taken at four different locations uniformly placed at the center of the annulus formed by the fan hub and the fan housing to evaluate the uniformity of the air temperature at the fan inlet. The thermocouples should be placed approximately 3 mm to 8 mm [0.1 to 0.3 in] above the fan hub vertically and halfway between the fan hub and the fan housing horizontally as shown in

Figure 6 (avoiding the hub spokes). Using an open bench to characterize an

and active heatsink can be useful, and usually ensures more uniform temperatures at the fan inlet. However, additional tests that include a solid barrier above the test motherboard surface can help evaluate the potential impact of the chassis. This barrier is typically clear Plexiglas*, extending at least 100 mm [4 i n ] in all directions beyond the edge of the thermal solution. Typical distance from the motherboard to the barrier is 81 mm [3.2 in]. For even more realistic airflow, the motherboard should be populated with significant elements like memory cards, graphic card, and chipset

is defined as the heatsink approach air

Figure 5

26 Thermal and Mechanical Design Guidelines

Thermal Metrology

heatsink. If a barrier is used, the thermocouple can be taped directly to the barrier with a clear tape at the horizontal location as previously described, half way between the fan hub and the fan housing. If a variable speed fan is used, it may be useful to add a thermocouple taped to the barrier above the location of the temperature sensor used by the fan to check its speed setting against air temperature. When measuring

in a chassis with a live motherboard, add-in cards, and other system components,

it is likely that the T distribution across the inlet fan section.

For passive heatsinks, thermocouples should be placed approximately 13 mm to 25 mm [0.5 to 1.0 in] away from processor and heatsink as shown in thermocouples should be placed approximately 51 mm [2.0 in] above the baseboard. This placement guideline is meant to minimize the effect of localized hot spots from baseboard components.

Note: Testing an active heatsink with a variable speed fan can be done in a thermal chamber

to capture the worst-case thermal environment scenarios. Otherwise, when doing a bench top test at room temperature, the fan regulation prevents the heatsink from operating at its maximum capability. To characterize the heatsink capability in the worst-case environment in these conditions, it is then necessary to disable the fan regulation and power the fan directly, based on guidance from the fan supplier.

measurements will reveal a highly non-uniform temperature

Figure 7. The

Figure 5. Locations for Measuring Local Ambient Temperature, Active Heatsink

NOTE: Drawing Not to Scale

Thermal and Mechanical Design Guidelines 27

LGA775 Socket Heatsink Loading

Figure 6. Locations for Measuring Local Ambient Temperature, Liquid-Cooling Heat

Exchanger

Side View

Airflow

Heat

Exchanger

Front View

NOTE: Drawing Not to Scale

Figure 7. Locations for Measuring Local Ambient Temperature, Passive Heatsink

Fan Hub Spokes

Measure TA as

indicated between the

hub spokes at mid-

blade length

NOTE: Drawing Not to Scale

28 Thermal and Mechanical Design Guidelines

Thermal Metrology

3.4 Processor Case Temperature Measurement Guidelines

To ensure functionality and reliability, the processor is specified for proper operation when T measurement location for T location for T

Special care is required when measuring TC to ensure an accurate temperature measurement. Thermocouples are often used to measure T measurements are made, the thermocouples must be calibrated, and the complete measurement system must be routinely checked against known standards. When measuring the temperature of a surface that is at a different temperature from the surrounding local ambient air, errors could be introduced in the measurements. The measurement errors could be caused by poor thermal contact between the junction of the thermocouple and the surface of the integrated heat spreader, heat loss by radiation, convection, by conduction through thermocouple leads, or by contact between the thermocouple cement and the heatsink base.

Appendix D defines a reference procedure for attaching a thermocouple to the IHS of

a 775-Land LGA processor package for T account the specific features of the 775-Land LGA package and of the LGA775 socket for which it is intended.

is maintained at or below the thermal profile as listed in the datasheet. The

measurement.

is the geometric center of the IHS. Figure 2 shows the

. Before any temperature

measurement. This procedure takes into

Thermal and Mechanical Design Guidelines 29

LGA775 Socket Heatsink Loading

30 Thermal and Mechanical Design Guidelines

Thermal Management Logic and Thermal Monitor Feature

4 Thermal Management Logic and

Thermal Monitor Feature

4.1 Processor Power Dissipation

An increase in processor operating frequency not only increases system performance, but also increases the processor power dissipation. The relationship between frequency and power is generalized in the following equation: P = CV P = power, C = capacitance, V = voltage, F = frequency). From this equation, it is evident that power increases linearly with frequency and with the square of voltage. In the absence of power saving technologies, ever increasing frequencies will result in processors with power dissipations in the hundreds of watts. Fortunately, there are numerous ways to reduce the power consumption of a processor, and Intel is aggressively pursuing low power design techniques. For example, decreasing the operating voltage, reducing unnecessary transistor activity, and using more power efficient circuits can significantly reduce processor power consumption.

F (where

An on-die thermal management feature called Thermal Monitor is available on the processor. It provides a thermal management approach to support the continued increases in processor frequency and performance. By using a highly accurate on-die temperature sensing circuit and a fast acting Thermal Control Circuit (TCC), the processor can rapidly initiate thermal management control. The Thermal Monitor can reduce cooling solution cost, by allowing thermal designs to target TDP.

The processor also supports an additional power reduction capability known as Thermal Monitor 2 described in Section

4.2.3.

4.2 Thermal Monitor Implementation

The Thermal Monitor consists of the following components:

• A highly accurate on-die temperature sensing circuit

• A bi-directional signal (PROCHOT#) that indicates if the processor has exceeded

its maximum temperature or can be asserted externally to activate the Thermal Control Circuit (TCC) (see Section 4.2.1 for more details on user activation of TCC via PROCHOT# signal)

•

FORCEPR# signal that will activate the TCC.

• A Thermal Control Circuit that will attempt to reduce processor temperature by

rapidly reducing power consumption when the on-die temperature sensor indicates that it has exceeded the maximum operating point.

Registers to determine the processor thermal status.

•

Thermal and Mechanical Design Guidelines 31

4.2.1 PROCHOT# Signal

The primary function of the PROCHOT# signal is to provide an external indication that the processor has exceeded its maximum operating temperature. While PROCHOT# is asserted, the TCC will be active. Assertion of the PROCHOT# signal is independent of any register settings within the processor. It is asserted any time the processor die temperature reaches the trip point.

PROCHOT# can be configured via BIOS as an output or bi-directional signal. As an output, PROCHOT# will go active when the processor temperature of either core exceeds its maximum operating temperature. This indicates the TCC has been activated. As an input, assertion of PROCHOT# will activate the TCC for both cores. The TCC will remain active until the system de-asserts PROCHOT#

The temperature at which the PROCHOT# signal goes active is individually calibrated during manufacturing. The power dissipation of each processor affects the set point temperature. The temperature where PROCHOT# goes active roughly parallels the thermal profile. Once configured, the processor temperature at which the PROCHOT# signal is asserted is not re-configurable.

One application is the thermal protection of voltage regulators (VR). System designers can create a circuit to monitor the VR temperature and activate the TCC when the temperature limit of the VR is reached. By asserting PROCHOT# (pulledlow) or FORCEPR#, which activates the TCC, the VR can cool down as a result of reduced processor power consumption. Bi-directional PROCHOT# can allow VR thermal designs to target maximum sustained current instead of maximum current. Systems should still provide proper cooling for the VR, and rely on bi-directional PROCHOT# signal only as a backup in case of system cooling failure.

LGA775 Socket Heatsink Loading

Note: A thermal solution designed to meet the thermal profile targets should rarely

experience activation of the TCC as indicated by the PROCHOT# signal going active.

4.2.2 Thermal Control Circuit

The Thermal Control Circuit portion of the Thermal Monitor must be enabled for the processor to operate within specifications. The Thermal Monitor’s TCC, when active, will attempt to lower the processor temperature by reducing the processor power consumption. In the original implementation of thermal monitor this is done by changing the duty cycle of the internal processor clocks, resulting in a lower effective frequency. When active, the TCC turns the processor clocks off and then back on with a predetermined duty cycle. The duty cycle is processor specific, and is fixed for a particular processor. The maximum time period the clocks are disabled is ~3 μs. This time period is frequency dependent and higher frequency processors will disable the internal clocks for a shorter time period. the internal processor clocks and PROCHOT#.

Performance counter registers, status bits in model specific registers (MSRs), and the PROCHOT# output pin are available to monitor the Thermal Monitor behavior.

Figure 8 illustrates the relationship between

32 Thermal and Mechanical Design Guidelines

Thermal Management Logic and Thermal Monitor Feature

Figure 8. Concept for Clocks under Thermal Monitor Control

PROCHOT#

ormal cloc

Internal clock Duty cycle control

Resultant internal clock

4.2.3 Thermal Monitor 2

The processor supports an enhanced Thermal Control Circuit. In conjunction with the existing Thermal Monitor logic, this capability is known as Thermal Monitor 2. This enhanced TCC provides an efficient means of reducing the power consumption within the processor and limiting the processor temperature.

When Thermal Monitor 2 is enabled, and a high temperature situation is detected, the enhanced TCC will be activated. The enhanced TCC causes the processor to adjust its operating frequency (by dropping the bus-to-core multiplier to its minimum available value) and input voltage identification (VID) value. This combination of reduced frequency and VID results in a reduction in processor power consumption.

A processor enabled for Thermal Monitor 2 includes two operating points, each consisting of a specific operating frequency and voltage. The first operating point represents the normal operating condition for the processor.

The second operating point consists of both a lower operating frequency and voltage. When the TCC is activated, the processor automatically transitions to the new frequency. This transition occurs very rapidly (on the order of 5 microseconds). During the frequency transition, the processor is unable to service any bus requests, all bus traffic is blocked. Edge-triggered interrupts will be latched and kept pending until the processor resumes operation at the new frequency.

Once the new operating frequency is engaged, the processor will transition to the new core operating voltage by issuing a new VID code to the voltage regulator. The voltage regulator must support VID transitions in order to support Thermal Monitor 2. During the voltage change, it will be necessary to transition through multiple VID codes to reach the target operating voltage. Each step will be one VID table entry (i.e., 12.5 mV steps). The processor continues to execute instructions during the voltage transition. Operation at the lower voltage reduces the power consumption of the processor, providing a temperature reduction.

Thermal and Mechanical Design Guidelines 33

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Once the processor has sufficiently cooled, and a minimum activation time has expired, the operating frequency and voltage transition back to the normal system operating point. Transition of the VID code will occur first, in order to insure proper operation once the processor reaches its normal operating frequency. Refer to Figure 9 for an illustration of this ordering.

Refer to the datasheet for further information on Thermal Monitor 2.

Figure 9. Thermal Monitor 2 Frequency and Voltage Ordering

TM2

Temperature

PROCHOT#

MAX

TM2

Frequency

VID

TM2

Time

4.2.4 Operation and Configuration

To maintain compatibility with previous generations of processors, which have no integrated thermal logic, the Thermal Control Circuit portion of Thermal Monitor is disabled by default. During the boot process, the BIOS must enable the Thermal Control Circuit. Thermal Monitor must be enabled to ensure proper processor operation.

The Thermal Control Circuit feature can be configured and monitored in a number of ways. OEMs are required to enable the Thermal Control Circuit while using various registers and outputs to monitor the processor thermal status. The Thermal Control Circuit is enabled by the BIOS setting a bit in an MSR (model specific register). Enabling the Thermal Control Circuit allows the processor to attempt to maintain a safe operating temperature without the need for special software drivers or interrupt handling routines. When the Thermal Control Circuit has been enabled, processor power consumption will be reduced after the thermal sensor detects a high temperature, i.e. PROCHOT# assertion. The Thermal Control Circuit and PROCHOT# transitions to inactive once the temperature has been reduced below the thermal trip point, although a small time-based hysteresis has been included to prevent multiple PROCHOT# transitions around the trip point. External hardware can monitor

VID

34 Thermal and Mechanical Design Guidelines

Thermal Management Logic and Thermal Monitor Feature

PROCHOT# and generate an interrupt whenever there is a transition from active-toinactive or inactive-to-active. PROCHOT# can also be configured to generate an internal interrupt which would initiate an OEM supplied interrupt service routine. Regardless of the configuration selected, PROCHOT# will always indicate the thermal status of the processor.

The power reduction mechanism of thermal monitor can also be activated manually using an “on-demand” mode. Refer to Section

4.2.5 On-Demand Mode

For testing purposes, the thermal control circuit may also be activated by setting bits in the ACPI MSRs. The MSRs may be set based on a particular system event (e.g., an interrupt generated after a system event), or may be set at any time through the operating system or custom driver control thus forcing the thermal control circuit on. This is referred to as “on-demand” mode. Activating the thermal control circuit may be useful for thermal solution investigations or for performance implication studies. When using the MSRs to activate the on-demand clock modulation feature, the duty cycle is configurable in steps of 12.5%, from 12.5% to 87.5%.

For any duty cycle, the maximum time period the clocks are disabled is ~3 μs. This time period is frequency dependent, and decreases as frequency increases. To achieve different duty cycles, the length of time that the clocks are disabled remains constant, and the time period that the clocks are enabled is adjusted to achieve the desired ratio. For example, if the clock disable period is 3 µs, and a duty cycl e of ¼ (25%) is selected, the clock on time would be reduced to approximately 1 μs [on time (1 μs) ÷ total cycle time (3 + 1) μs = ¼ duty cycle]. Similarly, for a duty cycle of 7/8 (87.5%), the clock on time would be extended to 21 μs [21 ÷ (21 + 3) = 7/8 duty cycle].

In a high temperature situation, if the thermal control circuit and ACPI MSRs (automatic and on-demand modes) are used simultaneously, the fixed duty cycle determined by automatic mode would take precedence.

4.2.5 for details on this feature.

Note: On-demand mode can not activate the power reduction mechanism of Thermal

Monitor 2

4.2.6 System Considerations

Intel requires the Thermal Monitor and Thermal Control Circuit to be enabled for all processors. The thermal control circuit is intended to protect against short term thermal excursions that exceed the capability of a well designed processor thermal solution. Thermal Monitor should not be relied upon to compensate for a thermal solution that does not meet the thermal profile up to the thermal design power (TDP).

Each application program has its own unique power profile, although the profile has some variability due to loop decisions, I/O activity and interrupts. In general, compute intensive applications with a high cache hit rate dissipate more processor power than applications that are I/O intensive or have low cache hit rates.

The processor TDP is based on measurements of processor power consumption while running various high power applications. This data is used to determine those applications that are interesting from a power perspective. These applications are then evaluated in a controlled thermal environment to determine their sensitivity to

Thermal and Mechanical Design Guidelines 35

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activation of the thermal control circuit. This data is used to derive the TDP targets published in the processor datasheet.

A system designed to meet the thermal profile at TDP and T the processor datasheet greatly reduces the probability of real applications causing the thermal control circuit to activate under normal operating conditions. Systems that do not meet these specifications could be subject to more frequent activation of the thermal control circuit depending upon ambient air temperature and application power profile. Moreover, if a system is significantly under designed, there is a risk that the Thermal Monitor feature will not be capable of maintaining a safe operating temperature and the processor could shutdown and signal THERMTRIP#.

For information regarding THERMTRIP#, refer to the processor datasheet and to Section

4.2.8 of this Thermal Design Guidelines.

C-MAX

4.2.7 Operating System and Application Software Considerations

The Thermal Monitor feature and its thermal control circuit work seamlessly with ACPI compliant operating systems. The Thermal Monitor feature is transparent to application software since the processor bus snooping, ACPI timer, and interrupts are active at all times.

values published in

4.2.8 THERMTRIP# Signal

In the event of a catastrophic cooling failure, the processor will automatically shut down when the silicon temperature has reached its operating limit. At this point the system bus signal THERMTRIP# goes active and power must be removed from the processor. THERMTRIP# activation is independent of processor activity and does not generate any bus cycles. Refer to the processor datasheet for more information about THERMTRIP#.

The temperature where the THERMTRIP# signal goes active is individually calibrated during manufacturing. The temperature where THERMTRIP# goes active is roughly parallel to the thermal profile and greater than the PROCHOT# activation temperature. Once configured, the temperature at which the THERMTRIP# signal is asserted is neither re-configurable nor accessible to the system.

4.2.9 Cooling System Failure Warning

It may be useful to use the PROCHOT# signal as an indication of cooling system failure. Messages could be sent to the system administrator to warn of the cooling failure, while the thermal control circuit would allow the system to continue functioning or allow a normal system shutdown. If no thermal management action is taken, the silicon temperature may exceed the operating limits, causing THERMTRIP# to activate and shut down the processor. Regardless of the system design requirements or thermal solution ability, the Thermal Monitor feature must still be enabled to ensure proper processor operation.

36 Thermal and Mechanical Design Guidelines

Thermal Management Logic and Thermal Monitor Feature

4.2.10 Digital Thermal Sensor

The processor utilizes the Digital Thermal Sensor (DTS) as the on-die sensor to use for fan speed control (FSC). The DTS replaces the on-die thermal diode used in previous product. The DTS is monitoring the same sensor that activates the TCC (See Section The DTS value where TCC activation occurs is 0 (zero).

The DTS can be accessed by two methods. The first is via a MSR. The value read via the MSR is an unsigned number of degrees C away from TCC activation. The second method which is expected to be the primary method for FSC is via the PECI interface. The value of the DTS when read via the PECI interface is always negative and again is degrees C away from TCC activation.

4.2.2). Readings from the DTS are relative to the activation of the TCC.

A T the DTS is the same as with the on-die thermal diode:

The calculation of T value to sum with the T The BIOS only needs to read the T control device.

Figure 10. T

value will be provided for use with DTS. The usage model for T

CONTROL

If the Digital Thermometer is less than T

•

CONTROL,

the fan speed can be reduced.

• If the Digi tal Thermometer is greater than or equal to T

CONTROL,

then TC must be

CONTROL

maintained at or below the Thermal Profile for the measured power dissipation.

CONTROL

for Digital Thermometer

CONTROL

is slightly different from previous product. There is no base

located in the same MSR as used in previous processors.

OFFSET

MSR and provide this value to the fan speed

OFFSET

with

Multiple digital thermal sensors can be implemented within the package without adding a pair of signal pins per sensor as required with the thermal diode. The digital thermal sensor is easier to place in thermally sensitive locations of the processor than the thermal diode. This is achieved due to a smaller foot print and decreased sensitivity to noise. Since the DTS is factory set on a per-part basis there is no need for the health monitor components to be updated at each processor family.

Thermal and Mechanical Design Guidelines 37

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Note: Intel® Core™2 Extreme processor QX6800 B3 stepping and QX9770 C0 stepping do

not have an on-die thermal diode. The T

CONTROL

in the MSR is relevant only to the

DTS.

4.2.11 Platform Environmental Control Interface (PECI)

The PECI interface is a proprietary single wire bus between the processor and the chipset or other health monitoring device. At this time the digital thermal sensor is the only data being transmitted. For an overview of the PECI interface see PECI Feature Set Overview. For additional information on the PECI see the processor datasheet.

The PECI bus is available on pin G5 of the LGA 775 socket. Intel chipsets beginning with the ICH8 have included PECI host controller. The PECI interface and the Manageability Engine are key elements to the Intel

(Intel

QST), see Chapter 6 and the Intel® Quiet System Technology (Intel® QST)

Configuration and Tuning Manual.

Intel has worked with many vendors that provide fan speed control devices to provide PECI host controllers. Consult the local representative for your preferred vendor for their product plans and availability.

Quiet System Technology

38 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

5 Intel Thermal/Mechanical

Reference Design Information

The Intel Advanced Liquid Cooling Technology or ALCT is composed of three components: a liquid to air radiator type heat exchanger; a 12 0mm fan; and an integrated pump with cold plate. The heat exchanger is connected to the pump with flexible hoses.

The heart of the design is the integrated pump cold plate combination. The cold plate is nested within a centrifugal pump impeller. This unique design takes advantage of the radial pull of the impeller to provide a uniform flow across the cold plate. The inlet flow returning from the heat exchanger impinges on the center of the cold plate. The centrifugal impeller then pulls the fluid across and through the cold pl ate fins. The fins in turn act as an inducer for the impeller. The fluid is then accelerated through the impeller and collected in a double involute and returned to the exchanger.

There are several unique features of the design in addition to the integration of pump and cold plate. There are no dynamic seals in the pump. The impeller is an integral part of the motor and is directly driven through a magnetic couple. There are no seals between the upper and lower pump housings. The seal is a function of the molding process. The copper cold plate is molded into the lower housing. The metal to plastic seal is also a function of the molding process.

The unit is maintenance free. Through careful selection of materials and the unique heat exchanger design that contains a reservoir the units are sealed for life. In addition every unit is proof pressure tested, vacuum decay tested, helium leak checked and the motor RPM is verified.

5.1 Validation Results for the ATX Reference Design

The reference thermal solution is a liquid cooled design, with an integrated pump and cold-plate (or chiller) and a remote heat exchanger with an attached fan. This solution is called the Intel Advanced Liquid Cooling Technology Reference Design (Intel ALCT Reference Design).

The reference solution pump and cold-plate module is compliant with the reference ATX motherboard keep-out and height recommendations defined Section the tubing that carries the working fluid from the pump/cold-plate protrudes through this keep-out and the heat exchanger is located on the back panel of the chassis.

The solution comes as an integrated assembly. The major ALCT components are provided Figure 16.

Note: If this fan design is used in your product and you will deliver it to end use customers,

you have the responsibility to determine an adequate level of protection (e.g., protection barriers, a cage, or an interlock) against contact with the energized fan by the user during user servicing.

5.5 through

Thermal and Mechanical Design Guidelines 39

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5.1.1 Heatsink Performance

Table 2 provides the Intel ALCT Reference Design performance for the Intel® Core™2 Extreme processor QX6800 B3 Stepping and QX9770 C0 Stepping. The results are based on the test procedure described in Section 5.1.4.

The table also includes a TA assumption of 38 °C for the Intel reference thermal solution at the inlet to the heat exchanger fan discussed in Section ambient temperature to the chassis of 35 °C is assumed, resulting in a temperature rise, T (refer to Sections acoustics.

Table 2. Intel Liquid Cooled Reference Design Performance (ALCT)

, of 3 °C. Meeting TA and ΨCA targets can maximize processor performance

2.2, 2.4. and Chapter 4). Minimizing T

3.3. An external

, can lead to improved

Intel® Core™ 2 Extreme processor QX6800 B3 stepping 0.13 °C/W TA = 38 °C Intel® Core™ 2 Extreme processor QX9770 C0 stepping 0.13 °C/W TA = 38 °C

5.1.2 Acoustics

To optimize acoustic emission by the heat exchanger fan and pump, the reference design implements a variable speed fan and pump. A variable speed fan and pump allows the reference design performance to adjust for changes in processor utilization and ambient air conditions. The required fan speed necessary to meet thermal specifications can be controlled by the silicon sensor temperature and should comply with requirements in

Table 3. Acoustic Results

Fan Speed

PWM

(RPM)

100%

(3300)

25%

(900)

NOTES:

1. Acoustic performance is defined in terms of measured sound power (LwAm) as defined in ISO 9296 standard, and measured according to ISO 7779.

2. Pump speed represents 3 pulses per rotation and if read by MB circuitry that assumes 2 pulses per rotation. It will perceive its operating (rotating) faster than specified in the table (e.g., the real pump speed is 600 rpm, 3 pulses, but MB would report 900rpm per 2 pulses calculated.)

3. If only 3 pin headers are available on MB that operate at a constant 12 V, the fan and pump will operate at full speed and this condition does not represent the minimum speed.

The design is intended to run using 4 pin header PWM signals specified in Sections and

5.1.6.

4. If only one recommended to run the pump off of the 4 pin header and the fan off of the 3 pin header and to have both headers respond to the CPU temperature to deliver the performance indicated in

Processor Target Thermal

Performance, Ψca

(Mean + 3σ)

Assumption

Table 3.

Pump Speed

PWM

(RPM)

100%

(1700)

25%

(600)

4 pin header is available on MB (all others are 3 pin headers), it is

Table 3.

Acoustic Thermal

6.0BA 0.13 °C/W Maximum fan and pump

3.6BA ~0.23 °C/W Minimum fan and pump

Performance

Ψca

Descriptions

speed

5.1.5

40 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

This design does not use a fan hub thermistor. Additional acoustic improvements can be achieved at lower processor workload by using the T in section

2.2.3. Intel recommendation is to use the Fan Specification for 4 Wire PWM

CONTROL

Controlled Fans to implement fan speed control capability based on the digital thermal sensor. Refer to Chapter

6 for further details.

5.1.3 Altitude

The reference heatsink solutions were evaluated at sea level. However, many companies design products that must function reliably at high altitude, typically 1,500 m [5,000 ft] or more. Air-cooled temperature calculations and measurements at sea level must be adjusted to take into account altitude effects like variation in air density and overall heat capacity. This often leads to some degradation in thermal solution performance compared to what is obtained at sea level, with lower fan performance and higher surface temperatures. The system designer needs to account for altitude effects in the overall system thermal design to make sure that the T

requirement for the processor is met at the targeted altitude.

5.1.4 Reference Heatsink Thermal Validation

specifications described

The Intel reference heatsink was validated within the specific boundary conditions based on the methodology described Section

5.2, and using a thermal test vehicle

(refer to section Error! Reference source not found.). Thermal testing is done in a thermal chamber (due to the slight change in fluid

properties at elevated temperatures) on test fixtures to secure the heat exchangers at the appropriate ambient temperatures. Acoustic testing is completed in an ATX chassis representing a micro-tower configuration.

The test results, for a number of samples, are reported in terms of a worst-case mean + 3σ value for thermal characterization parameter using real processors (based on the thermal test vehicle correction factors).

Thermal and Mechanical Design Guidelines 41

5.1.5 Fan Motor Performance

The fan power requirements for proper operation are given Table 4.

Table 4. Fan Electrical Performance Requirements

Requirement Value

Maximum Average fan current draw 1.5 A Fan start-up current draw 2.2 A Fan start-up current draw maximum duration 1.0 second Fan header voltage 12 V ± 5% Tachometer output 2 pulse per revolution Tachometer output signal Open-collector (open-drain) PWM signal input frequency 21 kHz to 28 kHz PWM signal pull up in fan 3.3 V (recommended max);

PWM signal current source Imax = 5 mA (short circuit current) PWM signal maximum voltage for logic low VIL = 0.8 V PWM compliant function RPM must be within spec for specified duty

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5.25 V (absolute max)

cycle

In addition to comply with overall thermal requirements (see Section 5.1.1), and the general environmental reliability requirements (see Section 5.2) the fan should meet the following performance requirements:

•

Mechanical wear out represents the highest risk reliability parameter for fans. The

capability of the functional mechanical elements (ball bearing, shaft, and tower assembly) must be demonstrated to a minimum useful lifetime of 50,000 hours.

In addition to passing the environmental reliability tests described in Section 5.2,

•

the fan must demonstrate adequate performance after 7,500 on/off cycles with each cycle specified as 3 minutes on, 2 minutes off, at a temperature of 70 °C.

See the Fan Specification for 4-wire PWM Controlled Fans for additional details on the fan specification.

42 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

5.1.6 Pump Motor Performance

The pump power requirements for proper operation are given Table 5

Table 5. Pump Electrical Performance Requirements

Requirement Value

Maximum Average motor current draw 1.5 A Motor start-up current draw 2.2 A Motor header voltage 12 V ±5% Tachometer output 3 pulse per revolution Tachometer output signal Open-collector (open-drain) Tachometer output signal current sink capability 10 mA PWM signal input frequency 25 kHz (nominal)

PWM signal pull up in fan 3.3 V (recommended max)

PWM signal current source Imax = 5 mA

PWM signal maximum voltage for logic low VIL = 0.8 V PWM compliant function RPM must be within spec for specified

21 kHz to 28kHz (allowable range)

5.25 V (absolute max)

(short circuit current)

duty cycle

In addition to comply with overall thermal requirements (see section 5.1.1), the pump should meet the environment reliability requirements (see Section 5.2).

Thermal and Mechanical Design Guidelines 43

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5.2 Environmental Reliability Testing

5.2.1 Structural Reliability Testing

Structural reliability tests consist of unpackaged, board-level vibration and shock tests of a given thermal solution in the assembled state. The thermal solution should meet the specified thermal performance targets after these tests are conducted; however, the test conditions outlined here may differ from your own system requirements.

5.2.1.1 Random Vibration Test Procedure

Duration: 10 min/axis, 3 axes Frequency Range: 5 Hz to 500 Hz Power Spectral Density (PSD) Profile: 3.13 G RMS

Figure 11. Random Vibration PSD

0.1

PSD (g^2/Hz)

0.001

0.01

3.13GRMS (10 minutes per axis)

(20, 0.02)

(5, 0.01)

5 Hz

10 100 1000

Frequency (Hz)

(500, 0.02)

500 Hz

44 Thermal and Mechanical Design Guidelines

)

Intel Thermal/Mechanical Reference Design Information

5.2.1.2 Shock Test Procedure

Recommended performance requirement for a motherboard:

Quantity: 3 drops for + and - directions in each of 3 perpendicular axes (i.e.,

•

total 18 drops).

Profile: 50 G trapezoidal waveform, 11 ms duration, 170 in/sec minimum

•

velocity change.

Setup: Mount sample board on test fixture.

•

Figure 12. Shock Acceleration Curve

c c

l e

r a t

i o

(g)

5.2.1.2.1 Recommended Test Sequence

Each test sequence should start with components (i.e., motherboard, heatsink assembly, etc.) that have never been previously submitted to any reliability testing.

The test sequence should always start with a visual inspection after assembly, and BIOS/CPU/Memory test (refer to Section 5.2.3).

Prior to the mechanical shock & vibration test, the units under test should be preconditioned for 72 hours at 45 ºC. The pre-conditioning is intended to present the system burn-in and shipping/storage environment stress.

4 6

Time (milliseconds

10 12

The stress test should be followed by a visual inspection and then BIOS/CPU/Memory test.

Thermal and Mechanical Design Guidelines 45

5.2.1.2.2 Post-Test Pass Criteria

The post-test pass criteria are:

1. No significant physi cal damage to the pump assembly attach mechanism

(including such items as clip and motherboard fasteners).

The assembly must remain attached to the motherboard.

3. The assembly remains seated and its bottom remains mated flatly against IHS

surface. No visible gap between the heatsink base and processor IHS. No visible tilt of the heatsink with respect to its attach mechanism.

No signs of physical damage on motherboard surface due to impact of the

4. assembly or its attach mechanism.

No visible physical damage to the processor package.

6. Successful BIOS/Processor/memory test of post-test samples.

7. Thermal compliance testin g to demonstrate that the case temperature specification can be met.

5.2.2 Power Cycling

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Thermal performance degradation due to TIM degradation is evaluated using power cycling testing. The test is defined by 7500 cycles for the case temperature from room temperature (~23 ºC) to the maximum case temperature defined by the thermal profile at TDP. Thermal Test Vehicle (refer to Section Error! Reference source not

found.) is used for this test.

5.2.3 Reliability Testing

The ALCT solution is a complex assembly with multiple joints and injection molded plastic parts. The selection of materials for pump and tubing as well as joint designs are done to provide a liquid-tight environment and to minimize the loss of liquid to ambient through vapor transmission. A reservoir is included in the heat exchanger to mitigate the impact of the vapor transmission loss. The design approach that is used for the selection of tubing and for reservoir sizing based on reliability testing is shown

Table 6. The results of the reliability testing and their impact on thermal resistance

in pump motor performance and on pump integrity are summarized.

The complex assembly of ALCT and the sensitivity of reliability to manufacturing environment would require frequent verification of parts for reliability. The objective of the reliability testing of the design is to identify key failure mechanisms and to develop design paths to mitigate them under a reasonable set of use conditions. The reliability testing and results are not expected to represent the performance of the design and may require additional testing to verify the performance in a particular use condition environment.

46 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

A list of failure mechanisms that were considered in design reliability testing are:

1. Pump assembly cracking causing liquid loss

2. Vapor loss through plastic walls and joints causing liquid loss

3. Thermal performance degradation due to internal mechanisms affecting

CPU T

temperature

4. Pump motor and printed circuit board performance degradation affecting

the pump RPM

All of the above mechanisms are expected to be active during the pump operation and relatively inactive during the off mode and so all reliability testing needs to be performed with pump on. The fatigue mechanisms (# 1) are additionally excited by the cycling of temperature caused by on-off cycles. The real use condition is a combination of continuous operation and on-off cycling and for the purpose of testing can be separated into a) continuous operation and b) on-off power cycles. The liquid temperature during continuous operation can be estimated by the heat exchanger thermal resistance, TDP, and T

= 0.05 ºC /W gives T

speed and T

= 26 ºC is expected to be approximately the same. A typical on-off cycle

(e.g., at TA = 38 ºC, TDP = 130 W, and

= 45 ºC). The calculated T

LIQUID

can be assumed to be from ambient condition to T also controlled similar to a fan for acoustics and expected mean pump RPM was estimated to be 1450 (range = 600-1700). The pump speed of 1450 was used to simulate typical condition during with use condition.

when fan is at its low

LIQUID

= 45 ºC. The pump speed is

LIQUID

Note: The heat exchanger thermal resistance, Ψ

approaching the heat exchanger.

The complete test matrix is summarized in the were slightly accelerated to reduce duration for failure. The cracking mechanism #1 was accelerated significantly by running at 75 ºC. The T applying a film heater to the bottom of the pump assembly alone (tubing and heat exchanger were not included by a closed loop tube was used to provide impedance from pump outlet to inlet).

Table 6. The Reliability Test Matrix

Use Condition Test Conditions Pump Speed Included Failure

Continuous operation T T T

On-off cycles T

LIQUID

7500 cycles

= (T

– TA )/(CPU power). TA is the air

LIQUID

Table 6. The continuous operation tests

value was achieved by

LIQUID

Mechanisms

= 50 ºC 1450 2 = 50 ºC 1450 3, 4

= 75 ºC for 16

weeks

= 35-60 ºC,

1450 1

1450 1,2,3,4

Thermal and Mechanical Design Guidelines 47

5.2.3.1 Tubing Material Selection

Tubing material selection requires balancing several different criteria. The parameters that were considered were cost, flexibility, flammability and vapor transmissibility. Three different types of tubing materials were tested for liquid loss by connecting a know length of tubing to the ALCT pump and measuring the assembly weight prior to the start and periodically during the test to quantify the loss. The liquid evaporation and migration of vapor through the plastic walls to atmosphere is the mode of liquid loss that is affected by the internal structure of plastic and its wall thickness. The pumps were run at 1450 RPM and T accurate scale is required to measure the weekly losses that allow for the calculation of a loss rate.

LGA775 Socket Heatsink Loading

was maintained at 50 ºC. An extremely

LIQUID

The results for 3 different materials are summarized in configuration had the lowest loss rate of 0.25 grams/week and was chosen as the tubing material for ALCT. Material parameters are 3/8” internal diameter and 5/8” outer diameter (1/8” wall thickness).

Table 7. The Weekly Loss Rate of Different Tubing Materials

Tubing Material Loss Rate (grams/week)

Polyurethene 5.0

PVC 1.2

Norprene® 0.25

5.2.3.2 Reservoir Sizing

The liquid loss through vapor migration through the tubing walls and joints can be minimized but not eliminated as shown by the relatively impermeable material of Norprene needed for the assembly of the solution inside of a chassis. The effect of liquid loss can be mitigated at least for a reasonable operational life of the solution by providing a liquid reservoir. A continuous operation test at 50 ºC and 1450 RPM was conducted with assembly mass monitored every week to identify weekly mass loss rate. The assembly mass loss data with 3 samples for 7 weeks duration is shown in The data shows that average loss rate was 0.25-0.30 grams/week and is reasonably consistent for 3 samples. The reservoir size of 38 milli-liters (38 grams for water) was chosen to provide 152 weeks (approximately 3 years) of operational life. The pump is expected to have additional resilience to liquid loss prior to significant impact to thermal performance.

rubber. The metal tubing was not a good option due to the flexibility

Table 7. The Norprene® tubing

Figure 13.

48 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

Figure 13. The Assembly Cumulative Mass Loss Data in Continuous Operation Test at

50 ºC and 1450 RPM

2.5

2.0

1.5

1.0

0.5

Cumulative mass loss (grams)

0.0 02468

Week

The reservoir presence in assembly and its impact on thermal performance was also confirmed by drawing the liquid out in the increment of 5 mL and measuring thermal performance at each increment. The Thermal resistance data are shown in It can be seen that when the liquid of 65 mL or more is drawn, thermal resistance goes up significantly. The test verifies the role of reservoir in maintaining thermal performance with liquid loss up to the reservoir size of 38 mL and 27 mL beyond that.

Figure 14. Thermal Resistance Curve for Liquid Loss of Reservoir

Theta ca vs. fluid level

Pump-1 Pump-2 Pump-3

Figure 14.

1.200

1.000

0.800

0.600

0.400

Theta ca [C/W]

0.200

0.000 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80

Fluid Removed [ml]

Pump-1 Pump 3 Pump 2

Thermal and Mechanical Design Guidelines 49

The reservoir is located in the heat exchanger at its top as shown in Figure 15. An air spring or an accumulator is needed to prevent high-pressure situation due to operating or storage temperature changes. 8 mL air volume is provided on the top of the reservoir to develop an air spring that minimizes the sensitivity to temperature change on pump internal pressure.

Figure 15. Reservoir Location

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5.2.3.3 Reliability Test Results

The reliability test results are summarized in Table 8. A small sample size was used to evaluate design against reliability. Test results showed no assembly cracking failure in either continuous operation or on-off cycles. The liquid loss measured was smaller than the reservoir capability for either use condition. Thermal resistance showed change of -0.01 to +0.007 ºC /W which is insignificant compared to the measurement accuracy of approximately +/- 0.01 ºC /W. The pump motor and PCB also did not show significant RPM degradation. The pump internal mechanisms (e.g., corrosion) that affect thermal performance were not expected to be active with the cycling use condition only and so thermal performance after cycling test was not measured.

50 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

Table 8. Reliability Test Results

Use

Condition

Continuous Operation

On-off Cycles

Test Conditions Failure

= 75 ºC

LIQUID

for 16 weeks T

= 50 ºC 2 0.25-0.30 grams/week

LIQUID

= 50 ºC 3 Insignificant change in Ψca for 3

LIQUID

= 50 ºC 4 2% average RPM degradation after 8

LIQUID

= 35-60 ºC,

LIQUID

5500 cycles T

= 35-60 ºC,

LIQUID

5500 cycles

= 35-60 ºC,

LIQUID

7500 cycles

mechanism

1 0/10 failure

samples

weeks for 3 samples

1 0/3 failure

2 3 grams loss after all cycles for 3

samples

4 No RPM degradation for 0/3 samples

Results

5.2.4 Recommended BIOS/CPU/Memory Test Procedures

This test is to ensure proper operation of the product before and after environmental stresses, with the thermal mechanical enabling components assembled. The test shall be conducted on a fully operational motherboard that has not been exposed to any battery of tests prior to the test being considered.

Testing setup should include the following components, properly assembled and/or connected:

Appropriate system motherboard

•

• Processor

All enabling components, including socket and thermal solution parts

•

• Power supply

•

Disk drive

• Video card

DIMM

•

• Keyboard

• Monitor

The pass criterion is that the system under test shall successfully complete the checking of BIOS, basic processor functions and memory, without any errors.

Thermal and Mechanical Design Guidelines 51

LGA775 Socket Heatsink Loading

5.3 Material and Recycling Requirements

Material shall be resistant to fungal growth. Examples of non-resistant materials include cellulose materials, animal and vegetable based adhesives, grease, oi ls, and many hydrocarbons. Synthetic materials such as PVC formulations, certain polyurethane compositions (e.g., polyester and some polyethers), plastics which contain organic fillers of laminating materials, paints, and varnishes also are susceptible to fungal growth. If materials are not fungal growth resistant, then MILSTD-810E, Method 508.4 must be performed to determine material performance.

Material used shall not have deformation or degradation in a temperature life test. Any plastic component exceeding 25 grams must be recyclable per the European Blue

Angel recycling standards.

5.4 Safety Requirements

Heatsink and attachment assemblies shall be consistent with the manufacture of units that meet the safety standards:

UL Recognition-approved for flammability at the system level. All mechanical and

•

thermal enabling components must be a minimum UL94V-2 approved.

CSA Certification. All mechanical and thermal enabling components must have

•

CSA certification.

All components (in particular the heatsink fins) must meet the test requirements

•

of UL1439 for sharp edges.

If the International Accessibility Probe specified in IEC 950 can access the moving

•

parts of the fan, consider adding safety feature so that there is no risk of personal injury.

5.5 Geometric Envelope for Intel Reference ATX Thermal Mechanical Design

Figure 66, Figure 67, and Figure 68 in Appendix G gives detailed reference ATX/μATX motherboard keep-out information for the reference thermal/mechanical enabling design. These drawings include height restrictions in the enabling component region.

The maximum height of the reference solution above the motherboard is 71.12 mm [2.8 inches] except for the flexible hoses which transit the area to the heat exchanger which is mounted on the back panel, and is compliant with the motherboard primary side height constraints defined in the ATX Specification revision 2.2 and the microATX Motherboard Interface Specification revision 1.2 found at http://www.formfactors.org Figure 16 shows the Intel® ALCT Reference Design Major Components. The reference solution also requires suitable space to mount the heat exchanger fan combination on the back panel.

52 Thermal and Mechanical Design Guidelines

Figure 17 gives the required foot print on the back panel.

Intel Thermal/Mechanical Reference Design Information

Figure 16. Intel® ALCT Reference Design Major Components

Development vendor information for the Intel® ALCT Reference Solution is provided in

Appendix A.

Figure 17. Heat Exchanger Fan Combination Foot Print View

Thermal and Mechanical Design Guidelines 53

5.6 Reference Attach Mechanism

The ALCT pump is attached to the motherboard through the use of a backside stiffener plate. Prior to motherboard installation in the chassis the backside stiffener plate is attached with two screws. Once installed these screws remain installed unless the stiffener plate requires removal. After installation of the board into the chassis the pump and upper structure are secured to the motherboard and backside stiffener with two additional screws ( panel and is secured in place using four screws provided in the accessory kit. The heat exchanger can be mounted on most back panels that will accept 120 mm fans. The range of recommended positions of the heat exchanger relative to the pump is defined in

Figure 74.

Figure 18. Structure to Motherboard Interface

Figure 18). The heat exchanger is positioned on the back

LGA775 Socket Heatsink Loading

54 Thermal and Mechanical Design Guidelines

Intel Thermal/Mechanical Reference Design Information

5.7 Socket and Voltage Regulation Cooling Strategy

Consideration for the cooling of power delivery components and CPU socket needs to be addressed when using a remote heat exchanger. The use of a remote heat exchanger for processor cooling can remove the cooling air that the motherboard components around the socket need and traditionally get from an active heatsink directly attached to the processor IHS. The Intel ALCT Reference Design incorporates a voltage regulation and socket cooling scheme that eliminates the need for additional fan(s) on these components. The proximity of the remote heat exchanger on the rear panel of the ATX miniTower /Tower allows for direct impingement of airflow to the voltage regulation components. the fan’s pressure side and the heat exchanger inlet that is integrated into the heat exchanger design allows for air to be introduced directly to the VR region for cooling. This approach introduces an airflow path that doesn’t significantly impact the airflow through the heat exchanger due to the reduced total impedance the fan sees and the subsequent increase in the operating point of the fan. Effectively the fan operating point increase is near the flow that is delivered to the VR and socket.

Figure 19. Diagram of Location of Heat Exchanger VR and Socket Airflow Cooling

Feature

Figure 19 illustrates how a small gap or exit between

HX Fan

Built-in VR and Socket cooling feature

Pump/coldplate

I/O

This method of VR and socket cooling was validated by testing this configuration as well as not having a gap. Analysis indicates that the momentum component attributed with the pressurized airflow in the configuration shown in help the cooling flow penetrated the VR components down to the MB surface thus providing the best thermal performance.

VR HS

Socket

Figure 19 would

Thermal and Mechanical Design Guidelines 55

LGA775 Socket Heatsink Loading

Using the cooling approach on the Intel D975XBX2 Desktop Board the CPU current draw vs. heat exchanger fan speed is shown in

Figure 20 and Table 9 as well as the performance of not having this cooling feature. This was measured as the maximum current draw before the VR circuitry reaches its maximum temperature and asserts the PROCHOT# signal.

The socket has a maximum temperature specification to maintain proper electrical performance at the contacts. Based on this temperature the current capability is slightly reduced but still shows improved capability of over 20 A at 100% speed over not having this feature.

Figure 20. CPU Maximum Current Draw for Heat Exchanger Fan Speed

CPU max imum curre nt dra w capability

at 35C external ambient

190 180 170 160 150 140 130

CPU Cu r r en t (A)

120 110 100

0% 20% 40% 60% 80% 100% 120%

VR/Socket Cooling Feature No Cooling Feature

Hea t Excha nger Fa n S pee d (PWM)

Table 9. Maximum Estimated Processor Current Capability at 35 ºC External Ambient

Fan Speed (PWM) Max. Current Draw for

25% – VR Requirements 115 105 60% – VR Requirements 150 120 100% – VR Requirements 180 150 100% – Socket Requirements

NOTES:

1. Socket temperature requirement is based on the maximum temperature necessary for end of life socket electrical performance

(1)

165 140

Heat Exchanger with VR

and Socket Airflow

Cooling Feature (A)

Max. Current Draw for Heat Exchanger

and fan with no

Cooling Feature (A)

56 Thermal and Mechanical Design Guidelines

Intel® Quiet System Technology (Intel® QST)

6 Intel® Quiet System

Technology (Intel

In the Intel® 965 Express Chipset Family a new control algorithm for fan speed control is being introduced. It is composed of a Manageability Engine (ME) in the Graphics Memory Controller Hub (GMCH) which executes the Intel

(Intel circuits.

The ME provides integrated fan speed control in lieu of the mechanisms available in a SIO or a stand-alone ASIC. The Intel QST is time based as compared to the linear or state control used by the current generation of FSC devices.

A short discussion of Intel QST will follow along with thermal solution design recommendations. For a complete discussion of programming the Intel QST in the ME please consult the Intel Tuning Manual.

QST) algorithm and the ICH8 containing the sensor bus and fan control

Quiet System Technology (Intel® QST) Configuration and

QST)

Quiet System Technology

6.1 Intel® Quiet System Technology Algorithm

The objective of Intel QST is to minimize the system acoustics by more closely controlling the thermal sensors to the corresponding processor or chipset device T control algorithm and a Fan Output Weighting Matrix. The PID algorithm takes into account the difference between the current temperature and the target (T rate of change and direction of change to minimize the required fan speed change. The Fan Output Weighting Matrix utilizes the effects of each fan on a thermal sensor to minimize the required fan speed changes

Figure 21 shows in a very simple manner how Intel QST works. See the Intel® Quiet

System Technology (Intel

discussion of the inputs and response.

value. This is achieved by the use of a Proportional-Integral-Derivative (PID)

CONTROL

QST) Configuration and Tuning Manual for a detail

CONTROL

), the

Thermal and Mechanical Design Guidelines 57

Figure 21. Intel® Quiet System Technology Overview

LGA775 Socket Heatsink Loading

6.1.1 Output Weighting Matrix

Intel QST provides an Output Weighting Matrix that provides a means for a single thermal sensor to affect the speed of multiple fans. An example of how the matrix could be used is if a sensor located next to the memory is sensitive to changes in both the processor heatsink fan and a 2 matrix additional the Intel QST could command the processor thermal solution fan and

this 2

fan to both accelerate a small amount. At the system level these two small

fan in the system. By placing a factor in this

changes can result in a smaller change in acoustics than having a single fan respond to this sensor.

6.1.2 Proportional-Integral-Derivative (PID)

The use of Proportional-Integral-Derivative (PID) control algorithms allow the magnitude of fan response to be determined based upon the difference between current temperature readings and specific temperature targets. A major advantage of a PID Algorithm is the ability to control the fans to achieve sensor temperatures much closer to the T

Figure 22 is an illustration of the PID fan control algorithm. As illustrated in the figure, when the actual temperature is below the target temperature, the fan will slow down. The current FSC devices have a fixed temperature vs. PWM output relationship and miss this opportunity to achieve additional acoustic benefits. As the actual temperature starts ramping up and approaches the target temperature, the algorithm will instruct the fan to speed up gradually, but will not abruptly increase the fan speed to respond to the condition. It can allow an overshoot over the target temperature for a short period of time while ramping up the fan to bring the actual temperature to the target temperature. As a result of its operation, the PID control algorithm can enable an acoustic-friendly platform.

CONTROL

58 Thermal and Mechanical Design Guidelines

Intel® Quiet System Technology (Intel® QST)

Figure 22. PID Controller Fundamentals

Integral (time averaged)

RPM Temperature

Proportional

Proportional Error

Error

+ dPWM

dPWM

+ dPWM

Actual

Temperature

Limit

Limit Temperature

Temperature

Derivative (Slope)

Time

Fan

Speed

For a PID algorithm to work limit temperatures are assigned for each temperature sensor. For Intel QST the T limit temperature. The ME will measure the error, slope and rate of change using the equations below:

Proportional Error (P) = T

•

• Integral (I) = Time averaged error

• Derivative (D) = ΔTemp / ΔTime

Three gain values are used to control response of algorithm.

• Kp = proportional gain

• Ki = Integral gain

Kd = derivative gain

•

The Intel provides initial values for the each of the gain constants. In addition it provides a methodology to tune these gain values based on system response.

Finally the fan speed change will be calculated using the following formula: ΔPWM = -P*(Kp) – I*(Ki) + D*(Kd)

Quiet System Technology (Intel® QST) Configuration and Tuning Manual

for the processor and chipset are to be used as the

CONTROL

LIMIT

– T

ACTUAL

Thermal and Mechanical Design Guidelines 59

LGA775 Socket Heatsink Loading

6.2 Board and System Implementation of

Intel

To implement the board it must be configured as shown in Figure 23 and listed in the following bullets.

ME system (S0-S1) with Controller Link connected and powered

•

• DRAM with Channel A DIMM 0 installed and 2 MB reserved for Intel QST FW

SPI Flash with sufficient space for the Intel QST Firmware

•

SST-based thermal sensors to provide board thermal data for Intel QST algorithms

• Intel QST firmware

Figure 23. Intel® Quiet System Technology Platform Requirements

Quiet System Technology

execution

Processor

Intel® (G)MCH

Controller Link

DRAM

Intel® ICH8

Note: Simple Serial Transport (SST) is a single wire bus that is included in the ICH8 to

provide additional thermal and voltage sensing capability to the Manageability Engine (ME)

FSC

Control

SPI

Flash

SST

Sensor

60 Thermal and Mechanical Design Guidelines

Intel® Quiet System Technology (Intel® QST)

Figure 24 shows the major connections for a typical implementation that can support processors with digital thermal sensor or a thermal diode. In this configuration an SST Thermal Sensor has been added to read the on-die thermal diode that is in all of the processors in the 775-land LGA packages shipped before the Intel processor. With the proper configuration information, the ME can accommodate inputs from PECI or SST for the processor socket. Additional SST sensors can be added to monitor system thermal (see

Appendix F for BTX recommendations for placement).

Figure 24. Example Acoustic Fan Speed Control Implementation

Core™2 Duo

Intel has engaged with a number of major manufacturers of thermal / voltage sensors to provide devices for the SST bus. Contact your Intel Field Sales representative for the current list of manufacturers and visit their web sites or local sales representatives for a part suitable for your design.

Thermal and Mechanical Design Guidelines 61

LGA775 Socket Heatsink Loading

6.3 Intel® QST Configuration & Tuning

Initial configuration of the Intel QST is the responsibility of the board manufacturer. The SPI flash should be programmed with the hardware configuration of the motherboard and initial settings for fan control, fan monitoring, voltage and thermal monitoring. This initial data is generated using the Intel provided Configuration Tool

At the system integrator the Configuration Tool can be used again but this time to tune the Intel QST subsystem to reflect the shipping system configuration. In the tuning process the Intel QST can be modified to have the proper relationships between the installed fans and sensors in the shipping system. A Weighting Matrix Utility and Intel QST Log program are planned to assist in optimizing the fan management and achieve acoustic goal.

See your Intel field sales representative for availability of these tools.

6.4 Fan Hub Thermistor and Intel® QST

There is no closed loop control between Intel QST and the thermistor, but they can work in tandem to provide the maximum fan speed reduction. The BTX reference design includes a thermistor on the fan hub. This Variable Speed Fan curve will determine the maximum fan speed as a function of the inlet ambient temperature and by design provides a Ψ QST, by measuring the processor digital thermal sensor will command the fan to reduce speed below the VSF curve in response to processor workload. Conversely if the processor workload increases, the FSC will command the fan via the PWM duty cycle to accelerate the fan up to the limit imposed by the VSF curve. Care needs to be taken in BTX designs to ensure the fan speed at the minimum operating speed that sufficient air flow is being provided to support the other system components.

sufficient to meet the thermal profile of the processor. Intel

Figure 25. Digital Thermal Sensor and Thermistor

Variable Speed Fan (VSF) Curve

Full

Speed

(RPM)

Fan Speed

Operating

Full

Min.

Inlet Temperature (°C)

Fan Speed

Fan Speed Operating Range

Operating Range with FSC

with FSC

100 %

Min %

Fan Speed

(% PWM Duty Cycle)

62 Thermal and Mechanical Design Guidelines

LGA775 Socket Heatsink Loading

Appendix A LGA775 Socket Heatsink

A.1 LGA775 Socket Heatsink Considerations

Heatsink clip load is traditionally used for:

•

Mechanical performance in mechanical shock and vibration

⎯

Refer to Section 5.6 above for information on the structural design strategy

for the Intel ALCT Reference Design

•

Thermal interface performance

⎯

Required preload depends on TIM

⎯

Preload can be low for thermal grease

In addition to mechanical performance in shock and vibration and TIM performance, LGA775 socket requires a minimum heatsink preload to protect against fatigue failure of socket solder joints.

Solder ball tensile stress is originally created when, after inserting a processor into the socket, the LGA775 socket load plate is actuated. In addition, solder joint shear stress is caused by coefficient of thermal expansion (CTE) mismatch induced shear

loading. The solder joint compressive axial force (F preload helps to reduce the combined joint tensile and shear stress.

Overall, the heatsink required preload is the minimum preload needed to meet all of the above requirements: Mechanical shock and vibration and TIM performance AND LGA775 socket protection against fatigue failure.

) induced by the heatsink

axial

Thermal and Mechanical Design Guidelines 63

LGA775 Socket Heatsink Loading

A.2 Metric for Heatsink Preload for ATX/uATX

Designs Non-Compliant with Intel Reference Design

A.2.1 Heatsink Preload Requirement Limitations

Heatsink preload by itself is not an appropriate metric for solder joint force across various mechanical designs and does not take into account for example (not an exhaustive list):

Heatsink mounting hole span

•

Heatsink clip assembly stiffness and creep

• Board stiffness and creep

• Board stiffness is modified by fixtures like backing plate, chassis attach, etc.

Simulation shows that the solder joint force (F deflection measured along the socket diagonal. The matching of F

protect the LGA775 socket solder joint in temperature cycling is equivalent to matching a target MB deflection.

Therefore, the heatsink preload for LGA775 socket solder joint protection against fatigue failure can be more generally defined as the load required to create a target board downward deflection throughout the life of the product

) is proportional to the board

axial

required to

axial

This board deflection metric provides guidance for mechanical designs that differ from the reference design for ATX//µATX form factor.

A.2.2 Motherboard Deflection Metric Definition

Motherboard deflection is measured along either diagonal (refer to Figure 26): d = dmax – (d1 + d2)/2 d’ = dmax – (d’1 + d’2)/2 Configurations in which the deflection is measured are defined in the Table 10. To measure board deflection, follow industry standard procedures (such as IPC) for

board deflection measurement. Height gauges and possibly dial gauges may also be used.

64 Thermal and Mechanical Design Guidelines

LGA775 Socket Heatsink Loading

Table 10. Board Deflection Configuration Definitions

Configuration

Parameter

d_ref yes no BOL deflection, no

d_BOL yes yes BOL deflection with

d_EOL yes yes EOL deflection

Processor + Socket

load plate

BOL: Beginning of Life EOL: End of Life

Figure 26. Board Deflection Definition

Heatsink Parameter Name

preload

d’1

d’2

Thermal and Mechanical Design Guidelines 65

LGA775 Socket Heatsink Loading

A.2.3 Board Deflection Limits

Deflection limits for the ATX/µATX form factor are:

d_BOL - d_ref ≥ 0.09 mm and d_EOL - d_ref ≥ 0.15 mm

And

d’_BOL – d’_ref ≥ 0.09 mm and d_EOL’ – d_ref’ ≥ 0.15 mm

NOTES:

1. The heatsink preload must remain within the static load limits defined in the processor datasheet at all times.

2. Board deflection should not exceed motherboard manufacturer specifications.

A.2.4 Board Deflection Metric Implementation Example

This section is for illustration only, and relies on the following assumptions:

• 72 mm x 72 mm hole pattern of the reference design

• Board stiffness = 900 lb/in at BOL, with degradation that simulates board creep

over time

⎯ Though these values are representative, they may change with selected

material and board manufacturing process. Check with your motherboard vendor.

Clip stiffness assumed constant – No creep.

•

Using Figure 27, the heatsink preload at beginning of life is defined to comply with d_EOL – d_ref = 0.15 mm depending on clip stiffness assumption.

Note that the BOL and EOL preload and board deflection differ. This is a result of the creep phenomenon. The example accounts for the creep expected to occur in the motherboard. It assumes no creep to occur in the clip. However, there is a small amount of creep accounted for in the plastic fasteners. This situation is somewhat similar to the Intel Reference Design.

The impact of the creep to the board deflection is a function of the clip stiffness:

The relatively compliant clips store strain energy in the clip under the BOL preload

•

condition and tend to generate increasing amounts of board deflection as the motherboard creeps under exposure to time and temperature.

In contrast, the stiffer clips store very little strain energy, and therefore does not

•

generate substantial additional board deflection through life.

NOTES:

Board and clip creep modify board deflection over time and depends on board

1. stiffness, clip stiffness, and selected materials.

Designers must define the BOL board deflection that will lead to the correct end

2. of life board deflection

66 Thermal and Mechanical Design Guidelines

LGA775 Socket Heatsink Loading

Figure 27. Example: Defining Heatsink Preload Meeting Board Deflection Limit

A.2.5 Additional Considerations

Intel recommends to design to {d_BOL – d_ref = 0.15 mm} at BOL when EOL conditions are not known or difficult to assess

The following information is given for illustration only. It is based on the reference keep-out, assuming there is no fixture that changes board stiffness:

d_ref is expected to be 0.18 mm on average, and be as high as 0.22 mm As a result, the board should be able to deflect 0.37 mm minimum at BOL Additional deflection as high as 0.09 mm may be necessary to account for additional

creep effects impacting the board/clip assembly. As a result, designs could see as much as 0.50mm total downward board deflection under the socket.

In addition to board deflection, other elements need to be considered to define the space needed for the downward board total displacement under load, like the potential interference of through-hole mount component pin tails of the board with a mechanical fixture on the back of the board.

NOTES:

The heatsink preload must remain below the maximum load limit of the package

1. at all times (Refer to processor

Board deflection should not exceed motherboard manufacturer specifications.

datasheet)

Thermal and Mechanical Design Guidelines 67

LGA775 Socket Heatsink Loading

A.2.5.1 Motherboard Stiffening Considerations

To protect LGA775 socket solder joint, designers need to drive their mechanical design to:

Allow downward board deflection to put the socket balls in a desi rable force state

•

to protect against fatigue failure of socket solder joint (refer to sections

A.2.2, and A.2.3.)

Prevent board upward bending during mechanical shock event

•

• Define load paths that keep the dynamic load applied to the package within

specifications published in the processor datasheet

Limiting board deflection may be appropriate in some situations like:

Board bending during shock

•

• Board creep with high heatsink preload

However, the load required to meet the board deflection recommendation (refer to Section package maximum load specification. For example, such a situation may occur when using a backing plate that is flush with the board in the socket area, and prevents the board to bend underneath the socket.

A.2.3) with a very stiff board may lead to heatsink preloads exceeding

A.2.1,

A.3 Heatsink Selection Guidelines

Evaluate carefully heatsinks coming with motherboard stiffening devices (like backing plates), and conduct board deflection assessments based on the board deflection metric.

Solutions derived from the reference design comply with the reference heatsink preload, for example:

The Intel ALCT reference design available from licensed suppliers (refer to

•

Appendix H for contact information)

68 Thermal and Mechanical Design Guidelines

Heatsink Clip Load Metrology

Appendix B Heatsink Clip Load

Metrology

B.1 Overview

This section describes a procedure for measuring the load applied by the heatsink assembly on a processor package.

This procedure is recommended to verify the preload is within the design target range for a design, and in different situations. For example:

Heatsink preload for the LGA775 socket

•

• Quantify preload degradation under bake conditions.

Note: This document reflects the current metrology used by Intel. Intel is continuously

exploring new ways to improve metrology. Updates will be provided later as this document is revised as appropriate.

B.2 Test Preparation

B.2.1 Heatsink Preparation

Three load cells are assembled into the base of the heatsink under test, in the area interfacing with the processor Integrated Heat Spreader (IHS), using load cells equivalent to those listed in Section B.2.2.

To install the load cells, machine a pocket in the heatsink base, as shown

Figure 29. The load cells should be distributed evenly, as close as possible to the

and pocket walls. Apply wax around the circumference of each load cell and the surface of the pocket around each cell to maintain the load cells in place during the heatsink installation on the processor and motherboard (Refer to

The depth of the pocket depends on the height of the load cell used for the test. It is necessary that the load cells protrude out of the heatsink base. However, this protrusion should be kept minimal, as it will create additional load by artificially raising the heatsink base. The measurement offset depends on the whole assembly stiffness (i.e. motherboard, clip, etc.). Heatsink.

Figure 28

Figure 29).

Figure 30 shows an example using the

Note: When optimizing the heatsink pocket depth, the variation of the load cel l height

should also be taken into account to make sure that all load cells protrude equally from the heatsink base. It may be useful to screen the load cells prior to installation to minimize variation.

Thermal and Mechanical Design Guidelines 69

Heatsink Clip Load Metrology

)

Remarks: Alternate Heatsink Sample Preparation

As mentioned above, making sure that the load cells have minimum protrusion out of the heatsink base is paramount to meaningful results. An alternate method to make sure that the test setup will measure loads representative of the non-modified design is:

Machine the pocket in the heat sink base to a depth such that the tips of the load

•

cells are just flush with the heat sink base

Then machine back the heatsink base by around 0.25 mm [0.01”], so that the

•

load cell tips protrude beyond the base.

Proceeding this way, the original stack height of the heatsink assembly should be preserved. This should not affect the stiffness of the heatsink significantly.

Figure 28. Load Cell Installation in Machined Heatsink Base Pocket – Bottom View

Heatsink Base Pocket Diameter ~ 29 mm

[~1.15”]

Package IHS Outline (Top

Surface

Load Cells

70 Thermal and Mechanical Design Guidelines

Heatsink Clip Load Metrology

Figure 29. Load Cell Installation in Machined Heatsink Base Pocket – Side View

Wax to maintain load cell in position during heatsink installation

Height of pocket ~ height of selected load cell

Load cell protrusion

(Note: to be optimized depending on assembly stiffness)

Figure 30. Preload Test Configuration

Preload Fixture (copper core with milled out pocket)

Load Cells (3x)

Thermal and Mechanical Design Guidelines 71

B.2.2 Typical Test Equipment

Loa

Note

a Logge

r scann

Notes

For the heatsink clip load measurement, use equivalent test equipment to the one

Table 11.

listed

Table 11. Typical Test Equipment

Heatsink Clip Load Metrology

Item Description

Honeywell*-Sensotec* Model 13 subminiature load cells, compression only

Select a load range depending on load level being tested.

Part Number

(Model)

AL32 2BL

www.sensotec.com

l l

NOTES:

1. Select load range depending on expected load level. It is usually better, whenever possible, to operate in the high end of the load cell capability. Check with your load cell vendor for further information.

2. Since the load cells are calibrated in terms of mV/V, a data logger or scanner is required to supply 5 volts DC excitation and read the mV response. An automated model will take the sensitivity calibration of the load cells and convert the mV output into pounds.

3. With the test equipment listed above, it is possible to automate data recording and control with a 6101-PCI card (GPIB) added to the scanner, allowing it to be connected to a PC running LabVIEW* or Vishay's StrainSmart* software.

4. IMPORTANT: In addition to just a zeroing of the force reading at no applied load, it is important to calibrate the load cells against known loads. Load cells tend to drift. Contact your load cell vendor for calibration tools and procedure information.

5. When measuring loads under thermal stress (bake for example), load cell thermal capability must be checked, and the test setup must integrate any hardware used along with the load cell. For example, the Model 13 load cells are temperature compensated up to 71°C, as long as the compensation package (spliced into the load cell's wiring) is also placed in the temperature chamber. The load cells can handle up to 121°C (operating), but their uncertainty increases according to 0.02% rdg/°F.

(

)

Vishay* Measurements Group Model 6100 scanner with a 6010A strain card (one card required per channel).

Model 6100

B.3 Test Procedure Examples

The following sections give two examples of load measurement. However, this is not meant to be used in mechanical shock and vibration testing.

Any mechanical device used along with the heatsink attach mechanism will need to be included in the test setup (i.e., back plate, attach to chassis, etc.).

Prior to any test, make sure that the load cell has been calibrated against known loads, following load cell vendor’s instructions.

72 Thermal and Mechanical Design Guidelines

Heatsink Clip Load Metrology

B.3.1 Time-Zero, Room Temperature Preload

Measurement

1. Pre-assemble mechanical components on the board as needed prior to mounting

the motherboard on an appropriate support fixture that replicate the board attach to a target chassis

For example: standard ATX board should sit on ATX compliant stand-offs. If

⎯

the attach mechanism includes fixtures on the back side of the board, those must be included, as the goal of the test is to measure the load provided by the actual heatsink mechanism.

Install relevant test vehicle (TTV, processor) in the socket

3. Assemble the heatsink reworked with the load cells to motherboard as shown for

the heatsink example in

4. Collect continuous load cell data at 1 Hz for the duration of the test. A minimum

time to allow the load cell to settle is generally specified by the load vendors (often of order of 3 minutes). The time zero reading should be taken at the end of this settling time.

Record the preload measurement (total from all three l oad cells) at the target time

5. and average the values over 10 seconds around this target time as well, i.e. in the interval , for example over [target time – 5 seconds ; target time + 5 seconds].

Figure 30, and actuate attach mechanism.

B.3.2 Preload Degradation under Bake Conditions

This section describes an example of testing for potential clip load degradation under bake conditions.

Preheat thermal chamber to target temperature (45 ºC or 85 ºC for example)

2. Repeat time-zero, room temperature preload measurement

3. Place unit into preheated thermal chamber for specified time

4. Record continuous load cell data as follows:

⎯

Sample rate = 0.1 Hz for first 3 hrs

⎯

Sample rate = 0.01 Hz for the remainder of the bake test

5. Remove assembly from thermal chamber and set into room temperature conditions

Record continuous load cell data for next 30 minutes at sample rate of 1 Hz.

Thermal and Mechanical Design Guidelines 73

Heatsink Clip Load Metrology

74 Thermal and Mechanical Design Guidelines

Thermal Interface Management

Appendix C Thermal Interface

Management

To optimize a heatsink design, it is important to understand the impact of factors related to the interface between the processor and the heatsink base. Specifically, the bond line thickness, interface material area and interface material thermal conductivity should be managed to realize the most effective thermal solution.

C.1 Bond Line Management

Any gap between the processor integrated heat spreader (IHS) and the heatsink base degrades thermal solution performance. The larger the gap between the two surfaces, the greater the thermal resistance. The thickness of the gap is determined by the flatness and roughness of both the heatsink base and the integrated heat spreader, plus the thickness of the thermal interface material (for example thermal grease) used between these two surfaces and the clamping force applied by the heatsink attach clip(s).

C.2 Interface Material Area

The size of the contact area between the processor and the heatsink base will impact the thermal resistance. There is, however, a point of diminishing returns. Unrestrained incremental increases in thermal interface material area do not translate to a measurable improvement in thermal performance.

C.3 Interface Material Performance

Two factors impact the performance of the interface material between the processor and the heatsink base:

Thermal resistance of the material

•

• Wetting/filling characteristics of the material

Thermal resistance is a description of the ability of the thermal interface material to transfer heat from one surface to another. The higher the thermal resistance, the less efficient the interface material is at transferring heat. The thermal resistance of the interface material has a significant impact on the thermal performance of the overall thermal solution. The higher the thermal resistance, the larger the temperature drop is across the interface and the more efficient the thermal solution (heatsink, fan) must be to achieve the desired cooling.

The wetting or filling characteristic of the thermal interface material is its ability, under the load applied by the heatsink retention mechanism, to spread and fill the gap between the processor and the heatsink. Since air is an extremely poor thermal conductor, the more completely the interface material fills the gaps, the lower the temperature drops across the interface. In this case, thermal interface material area also becomes significant; the larger the desired thermal interface material area, the higher the force required to spread the thermal interface material.

Thermal and Mechanical Design Guidelines 75

Thermal Interface Management

76 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

Appendix D Case Temperature

Reference Metrology

D.1 Objective and Scope

This appendix defines a reference procedure for attaching a thermocouple to the IHS of a 775-land LGA package for T specific features of the 775-land LGA package and of the LGA775 socket for which it is intended. The recommended equipment for the reference thermocouple installation, including tools and part numbers are also provided.

measurement. This procedure takes into account the

Thermal and Mechanical Design Guidelines 77

Case Temperature Reference Metrology

D.2 Supporting Test Equipment

To apply the reference thermocouple attach procedure, it is recommended to use the equipment (or equivalent) given in the table below.

Item Description Part Number

Measurement and Output

Microscope Olympus* Light microscope or equivalent SZ-40 DMM Digital Multi Meter for resistance measurement Fluke 79 Series Thermal Meter Hand held thermocouple meter Multiple Vendors

Solder Station (see note 1 for ordering information)

Heater Block Heater assembly to reflow solder on IHS 30330 Heater WATLOW120V 150W Firerod 0212G G1A38-

Transformer Superior Powerstat transformer 05F857

L12

Miscellaneous Hardware

Solder Indium Corp. of America

Alloy 57BI / 42SN / 1AG 0.010 Diameter Flux Indium Corp. of America 5RMA Loctite* 498

Adhesive Adhesive

Accelerator Kapton* Tape For holding thermoco uple in place Not Available Thermocouple Omega *,36 gauge, “T” Type

Ice Point Cell Omega*, stable 0 ºC temperature source for

Hot Point Cell Omega *, temperature source to control and

NOTES:

1. The Solder Station consisting of the Heater Block, Heater, Press and Transformer are available from Jemelco Engineering 480-804-9514

2. This part number is a custom part with the specified insulation trimming and packaging requirements necessary for quality thermocouple attachment, See from Omega Anthony Alvarez, Direct phone (203) 359-7671, Direct fax (203) 9687142, E-Mail: aalvarez@omega.com

Super glue w/thermal characteristics 49850

Loctite* 7452 for fast glue curing 18490

(see note 2 for ordering information)

Calibration and Control

calibration and offset

understand meter slope gain

52124

OSK2K1280/5SR TC-TT-T-36-72

TRCIII

CL950-A-110

Figure 31. Order

78 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

Figure 31. Omega Thermocouple

D.3 Thermal Calibration and Controls

It is recommended that full and routine calibration of temperature measurement equipment be performed before attempting to perform case temperature measurements. Intel recommends checking the meter probe set against known standards. This should be done at 0 ºC (using ice bath or other stable temperature source) and at an elevated temperature, around 80 ºC (using an appropriate temperature source).

Wire gauge and length also should be considered as some less expensive measurement systems are heavily impacted by impedance. There are numerous resources available throughout the industry to assist with implementation of proper controls for thermal measurements.

NOTES:

It is recommended to follow company standard procedures and wear safety

1. items like glasses for cutting the IHS and gloves for chemical handling.

Ask your Intel field sales representative if you need assistance to groove

2. and/or install a thermocouple according to the reference process.

D.4 IHS Groove

Cut a groove in the package IHS according to the drawing given in Figure 32.

Thermal and Mechanical Design Guidelines 79

Case Temperature Reference Metrology

Figure 32. 775-LAND LGA Package Reference Groove Drawing

Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

The orientation of the groove relative to the package pin 1 indicator (gold triangle in one corner of the package) is shown.

Figure 33 for the 775-Land LGA package IHS.

Figure 33. IHS Groove on the 775-LAND LGA Package

Pin1

indicator

IHS Groove

When the processor is installed in the LGA775 socket, the groove is perpendicular to the socket load lever, and on the opposite side of the lever, as shown

Figure 34. IHS Groove Orientation Relative to the LGA775 Socket

Select a machine shop that is capable of holding drawing specified tolerances. IHS groove geometry is critical for repeatable placement of the thermocouple bead, ensuring precise thermal measurements. The specified dimensions minimize the impact of the groove on the IHS under the socket load. A larger groove may cause the IHS to warp under the socket load such that it does not represent the performance of an ungrooved IHS on production packages.

Figure 34.

Inspect parts for compliance to specifications before accepting from machine shop.

Thermal and Mechanical Design Guidelines 81

Case Temperature Reference Metrology

D.5 Thermocouple Attach Procedure

The procedure to attach a thermocouple with solder takes about 15 minutes to complete. Before proceeding turn on the solder block heater, as it can take up to 30 minutes to reach the target temperature of 153 – 155°C.

Note: To avoid damage to the TTV or processor ensure the IHS temperature does not

exceed 155 °C.

D.5.1 Thermocouple Conditioning and Preparation

1. Use a calibrated thermocouple as specified in Sections D.2 and D.3.

Under a microscope verify the thermocouple insulation meets the quality

2. requirements. The insulation should be about 1/16 inch (0.062 ± 0.030) from the end of the bead (

Figure 35. Inspection of Insulation on Thermocouple

Figure 35).

3. Measure the thermocouple resistance by holding both contacts on the connector on one probe and the tip of thermocouple to the other probe of the DMM (measurement should be about~3.0 ohms for 36-gauge type T thermocouple).

Straighten the wire for about 38 mm [1 ½ inch] from the bead.

82 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

5. Using the microscope and tweezers, bend the tip of the thermocouple at approximately 10 degree angle by about 0.8 mm [.030 inch] from the tip

Figure 36).

(

Figure 36. Bending the Tip of the Thermocouple

D.5.2 Thermocouple Attachment to the IHS

6. Clean groove and IHS with Isopropyl A lcohol (IPA) and a lint free cloth removing all residues prior to thermocouple attachment.

Place the thermocouple wire inside the groove; letting the exposed wire and bead

7. extend about 1.5 mm [0.030 inch] past the end of groove. Secure it with Kapton*

Figure 37). Clean the IHS with a swab and IPA.

tape (

8. Verify under the microscope that the thermocouple wires are straight and parallel in the groove and that the bead is still bent.

Figure 37. Securing Thermocouple Wires with Kapton* Tape Prior to Attach

Thermal and Mechanical Design Guidelines 83

9. Lift the wire at the middle of groove with tweezers and bend the front of wire to place the thermocouple in the groove ensuring the tip is in contact with the end and bottom of the groove in the IHS (

Figure 38. Thermocouple Bead Placement

(A)

Case Temperature Reference Metrology

Figure 38-A and B).

(B)

10. Place the package under the microscope to continue with process. It is also recommended to use a fixture (like processor tray or a plate) to help holding the unit in place for the rest of the attach process.

84 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

11. While still at the microscope, press the wire down about 6mm [0.125”] from the thermocouple bead using the tweezers or your finger. Place a piece of Kapton* tape to hold the wire inside the groove ( bead placement.

Figure 39. Position Bead on the Groove Step

Figure 39). Refer to Figure 40 for detailed

Kapton* tape

Figure 40. Detailed Thermocouple Bead Placement

TC Wire with Insulation

IHS with Groove

Wire section into the groove to prepare for final bead placement

TC Bead

Thermal and Mechanical Design Guidelines 85

Figure 41. Third Tape Installation

12. Place a 3rd piece of tape at the end of the step in the groove as shown in Figure 41. This tape will create a solder dam to prevent solder from flowing into the larger IHS groove section during the melting process.

Measure resistance from thermocouple end wires (hold both wires to a DMM

13. probe) to the IHS surface. This should be the same value as measured during the thermocouple conditioning Section D.5.1, step 3 (Figure 42)

Case Temperature Reference Metrology

Figure 42. Measuring Resistance between Thermocouple and IHS

86 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

14. Using a fine point device, place a small amount of flux on the thermocouple bead. Be careful not to move the thermocouple bead during this step ( the flux remains in the bead area only.

Figure 43. Applying Flux to the Thermocouple Bead

Figure 43). Ensure

15. Cut two small pieces of solder 1/16 inch (0.065 inch / 1.5 mm) from the roll usi n g tweezers to hold the solder while cutting with a fine blade(

Figure 44. Cutting Solder

Figure 44)

Thermal and Mechanical Design Guidelines 87

16. Place the two pieces of solder in parallel, directly over the thermocouple bead

Figure 45)

(

Figure 45. Positioning Solder on IHS

Case Temperature Reference Metrology

17. Measure the resistance from the thermocouple end wires again using the DMM (refer to Section

D.5.1, step 2) to ensure the bead is still properly contacting the

IHS.

D.5.3 Solder Process

18. Make sure the thermocouple that monitors the Solder Block temperature is positioned on the Heater block. Connect the thermocouple to a handheld meter to monitor the heater block temperature

Verify the temperature of the Heater block station has reached 155°C ±5°C before

19. you proceed.

Connect the thermocouple for the device being soldered to a second hand held

20. meter to monitor IHS temperature during the solder process.

88 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

Figure 46. Solder Station Setup

21. Remove the land side protective cover and place the device to be soldered in the solder station. Make sure the thermocouple wire for the device being soldered is exiting the heater toward you.

Note: Do not touch the copper heater block at any time as this is very hot.

22. Move a magnified lens light close to the device in the solder status to get a better view when the solder begins to melt.

Lower the Heater block onto the IHS. Monitor the device IHS temperature during

23. this step to ensure the maximum IHS temperature is not exceeded

Note: The target IHS temperature during reflow is 150°C ±3°C. At no time should the IHS

temperature exceed 155 °C during the solder process as damage to the device may occur.

Thermal and Mechanical Design Guidelines 89

24. You may need to move the solder back toward the groove as the IHS begins to heat. Use a fine tip tweezers to push the solder into the end of the groove until a solder ball is built up (

Figure 47 and Figure 48)

Figure 47. View Through Lens at Solder Station

Case Temperature Reference Metrology

Figure 48. Moving Solder back onto Thermocouple Bead

90 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

25. Lift the heater block and magnified lens, using tweezers quickly rotate the device 90 degrees clockwise. Using the back of the tweezers press down on the solder this will force out the excess solder

Figure 49. Removing Excess Solder

26. Allow the device to cool down. Blowing compressed air on the device can accelerate the cooling time. Monitor the device IHS temperature with a handheld meter until it drops below 50° C before moving it to the microscope for the final steps

D.5.4 Cleaning and Completion of Thermocouple

Installation

27. Remove the device from the solder station and continue to monitor IHS Temperature with a handheld meter. Place the device under the microscope and remove the three pieces of Kapton* tape with Tweezers, keeping the longest for re-use.

Straighten the wire and work the wire in to the groove. Bend the thermocouple

28. over the IHS. Replace the long piece of Kapton* tape at the edge of the IHS.

Note: The wire needs to be straight so it doesn’t sit above the IHS surface at anytime

Figure 50).

(

Thermal and Mechanical Design Guidelines 91

Figure 50. Thermocouple placed into groove

29. Using a blade carefully shave the excess solder above the IHS surface. Only shave in one direction until solder is flush with the groove surface (

Case Temperature Reference Metrology

Figure 51).

Figure 51. Removing Excess Solder

Note: Take usual precautions when using open blades

30.

Clean the surface of the IHS with Alcohol and use compressed air to remove any

remaining contaminants.

92 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

31. Fill the rest of the groove with Loctite* 498 Adhesive. Verify under the microscope that the thermocouple wire is below the surface along the entire length of the IHS groove (

Figure 52).

Figure 52. Filling Groove with Adhesive

32. To speed up the curing process apply Loctite* Accelerator on top of the Adhesive and let it set for a couple of minutes(

Figure 53. Application of Accelerant

Figure 53).

Thermal and Mechanical Design Guidelines 93

Figure 54. Removing Excess Adhesive from IHS

33. Using a blade, carefully shave any adhesive that is above the IHS surface

Figure 54). The preferred method is to shave from the edge to the center of the

( IHS.

Case Temperature Reference Metrology

Note: The adhesive shaving step should be performed while the adhesive is partially cured,

but still soft. This will help to keep the adhesive surface flat and smooth with no pi ts or voids. If there are voids in the adhesive, refill the voids with adhesive and shave a second time.

34. Clean IHS surface with IPA and a wipe.

35. Clean the LGA pads with IPA and a wipe.

36. Replace the land side cover on the device.

37. Perform a final continuity test.

38. Wind the thermocouple wire into loops and secure or if provided by the vendor back onto the plastic roll. (

Figure 55).

Figure 55. Finished Thermocouple Installation

39. Place the device in a tray or bag until it’s ready to be used for thermal testing use.

94 Thermal and Mechanical Design Guidelines

Case Temperature Reference Metrology

D.6 Thermocouple Wire Management

When installing the processor into the socket, make sure that the thermocouple wires exit above the load plate as load plate and the IHS will likely damage the wires.

Note: When thermocouple wires are damaged, the resulting reading maybe wrong. For

example, if there are any cuts into the wires insulation where the wires are pinched between the IHS and the load plate, the thermocouple wires can get in contact at this location. In that case, the reported temperature would be the edge of the IHS/socket load plate area. This temperature is usually much lower than the temperature at the center of the IHS.

Prior to installing the heatsink, make sure that the thermocouple wires remain below the IHS top surface, by running a flat blade on top of the IHS for example.

Figure 56. Thermocouple Wire Management

Figure 56. Pinching the thermocouple wires between the

Thermal and Mechanical Design Guidelines 95

Case Temperature Reference Metrology

96 Thermal and Mechanical Design Guidelines

Legacy Fan Speed Control

Appendix E Legacy Fan Speed

Control

A motherboard design may opt to use a SIO or ASIC based fan speed control device that uses the existing look up or state based fan speed control.

The fan speed control implementations consist of the following items

• A motherboard designed with a fan speed controller with the following

functionality:

PWM fan control output

⎯ ⎯

Remote digital thermal sensor measurement capability over the PECI bus.

A motherboard with a 4 pin fan header for the processor heatsink fan.

•

• Processor heatsink with 4–wire PWM controlled Fan.

A thermistor in the fan hub is recommended, but not a requirement. The reference solution and the Boxed Processor will implement a thermistor into the design.

The following sections will discuss the necessary steps to implement Legacy Fan Speed Control.

E.1 Thermal Solution Design

The first step is to select or design a processor thermal solution that meets the thermal profile for the processor. See Section profile and consult the processor datasheet for the specific values.

The designer needs to ensure that when the heat sink fan is operating at full speed the thermal solution will meet the T profile will allow the designer to make tradeoffs in thermal performance versus the inlet temperature to the processor fan heatsink.

limits at TDP. The slope of the thermal

C-MAX

E.1.1 Determine Thermistor Set Points

A thermistor implemented in the hub of a fan is a first level of fan speed control. It provides an easy and cost effective means to begin acoustic noise reduction. It will, by design, run the fan at an appropriate speed based on the ambient conditions.

Chapter fan speed based on temperature to ensure that T at a given ambient temperature. The resulting variable speed fan (VSF) curve is the upper limit on fan speed.

The benefit of this upper limit will become more apparent when the fan speed controller is responding to the digital thermal sensor.

5 discussed in detail the reference thermal solution, including the target Ψ

2.2.2 for the definition of the thermal

is not exceeded for TDP power

C-MAX

Thermal and Mechanical Design Guidelines 97

Figure 57. Thermistor Set Points

Full

Speed

(RPM)

Fan Speed

Min.

Operating

Legacy Fan Speed Control

Variable Speed Fan (VSF) Curve

Fan Inlet

Temperature (°C)

E.1.2 Minimum Fan Speed Set Point

The final aspect of thermal solution design is to determine the minimum speed the fan will be allowed to operate. This value can be driven by the cooling requirements for another portion of the design, such as the processor voltage regulator, or by functional limits of the fan design.

Per the Fan Specification for 4 wire PWM Controlled Fans; there are three possible options to consider

Type A: The fan will run at minimum RPM for all PWM duty cycle values less than

•

minimum duty cycle. This would be programmed into the fan controller located on the fan hub. It can not be overridden by the external fan speed control.

Type B: The fan will run at minimum RPM for all non-zero PWM duty cycle values

•

less than minimum duty cycle and turn off the fan at 0% PWM duty cycle.

Type C: The fan will stop running when the current provided to the motor

•

windings is insufficient to support commutation. The fan would turn off at 0% PWM duty cycle input.

For the reference thermal solution Type A was implemented.

98 Thermal and Mechanical Design Guidelines

Legacy Fan Speed Control

E.2 Board and System Implementation

Once the thermal solution is defined, the system designer and board designer can define the fan speed control implementation. The first step is to select the appropriate fan speed controller (FSC). typical implementation.

Figure 58. Example Fan Speed Control Implementation

Figure 58 shows the major connections for a

A number of major manufacturers have FSC components that include the necessary functionality to measure the temperature of the digital thermal sensor via the PECI interface and output a PWM signal. These components can be a discrete device or a super IO (SIO) with the functionality embedded. Intel has engaged with a number of major manufacturers of FSC components to provide devices that have a PECI host controller. Please contact your Intel Field Sales representative for the current list of manufacturers and visit their web sites or contact your local sales representatives for a part suitable for your design.

E.2.1 Choosing Fan Speed Control Settings

Fan speed control algorithms allow the system thermal engineer a number of options to consider. The typical control settings that need to be considered are:

The temperature when the fan will begin to accelerate in response to the digital

•

thermal sensor temperature (T

•

The temperature where the fan is operating at full speed (100% PWM duty cycle).

By specification this is T

CONTROL

• The minimum fan speed (PWM duty cycle). For any digital thermal sensor

temperature less than T

the fan will run at this speed

LOW

)

Thermal and Mechanical Design Guidelines 99

These are the minimum parameters required to implement acoustic fan speed control.

Figure 59 for an example. There may be vendor specific options that offer

See enhanced functionality. See the appropriate vendor datasheet on how to implement those features.

Figure 59. Fan Speed Control

Legacy Fan Speed Control

Full Speed

(RPM)

Fan Speed

Min Speed

LOW

Diode Temperature

(°C)

CONTROL

E.2.1.1 Temperature to Begin Fan Acceleration

The first item to consider is the value for T temperature to set as the threshold to begin increasing PWM duty cycle to the fan.

. The FSC device needs a minimum

LOW

100 %

X %

Fan Speed

(% PWM Duty Cycle)

The system designer might initially consider a small temperature range (T

= T

LOW

the longest time after an increase in T

), 5°C to accelerate the fan. That would delay the fan accelerating for

RANGE

. There are a number of issues that

SENSOR

CONTROL

–

should be considered with this strategy

There is little granularity in the fan speeds. For each 1°C of i ncrease in diode

•

temperature = 20% jump in PWM duty cycle %

Fan speed oscillation as the thermal solution chases the digital thermal sensor

•

temperature

Having T

•

SENSOR

overshoot T

and the thermal profile causing the Thermal

CONTROL

Control Circuit to activate to reduce the temperature.

In extreme cases Thermtrip# activates and shuts down the processor

•

The first two cases can create a poor acoustic response for the user. The third case the user could notice a drop in performance as the thermal control circuit reduces the power. The

Figure 60 is an example of this situation. The system begins at idle and

the Maxpower program is started at 65% workload.

100 Thermal and Mechanical Design Guidelines

Intel QX9770 - Core 2 Extreme Quad-Core Processor, QX68000 Core 2 Extreme Design Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

1 Introduction

1.1 Document Goals and Scope

1.1.1 Importance of Thermal Management

1.1.2 Document Goals

1.1.3 Document Scope

1.2 References

1.3 Definition of Terms

Processor Thermal/Mechanical Information

2.1 Mechanical Requirements

2.1.1 Processor Package

2.1.2 Heatsink Attach

2.1.2.1 General Guidelines

2.1.2.2 The Pump Assembly Clip Load Requirement

2.1.2.3 Additional Guidelines

2.2 Thermal Requirements

2.2.1 Processor Case Temperature

2.2.2 Thermal Profile

2.3 Heatsink Design Considerations

2.3.1 Heatsink Size

2.3.2 Package IHS Flatness

2.3.3 Thermal Interface Material

2.4 System Thermal Solution Considerations

2.4.1 Chassis Thermal Design Capabilities

2.4.2 Improving Chassis Thermal Performance

2.4.3 Summary

2.5 System Integration Considerations

3 Thermal Metrology

3.1 Characterizing Cooling Performance Requirements

3.1.1 Example

3.2 Processor Thermal Solution Performance Assessment

3.3 Local Ambient Temperature Measurement Guidelines

3.4 Processor Case Temperature Measurement Guidelines

Thermal Management Logic and Thermal Monitor Feature

4.1 Processor Power Dissipation

4.2 Thermal Monitor Implementation

4.2.1 PROCHOT# Signal

4.2.2 Thermal Control Circuit

4.2.3 Thermal Monitor 2

4.2.4 Operation and Configuration

4.2.5 On-Demand Mode

4.2.6 System Considerations

4.2.7 Operating System and Application Software Considerations

4.2.8 THERMTRIP# Signal

4.2.9 Cooling System Failure Warning

4.2.10 Digital Thermal Sensor

4.2.11 Platform Environmental Control Interface (PECI)

Intel Thermal/Mechanical Reference Design Information

5.1 Validation Results for the ATX Reference Design

5.1.1 Heatsink Performance

5.1.2 Acoustics

5.1.3 Altitude

5.1.4 Reference Heatsink Thermal Validation

5.1.5 Fan Motor Performance

5.1.6 Pump Motor Performance

5.2 Environmental Reliability Testing

5.2.1 Structural Reliability Testing

5.2.1.1 Random Vibration Test Procedure

5.2.1.2 Shock Test Procedure

5.2.2 Power Cycling

5.2.3 Reliability Testing

5.2.3.1 Tubing Material Selection

5.2.3.2 Reservoir Sizing

5.2.3.3 Reliability Test Results

5.2.4 Recommended BIOS/CPU/Memory Test Procedures

5.3 Material and Recycling Requirements

5.4 Safety Requirements

5.5 Geometric Envelope for Intel Reference ATX Thermal Mechanical Design

5.6 Reference Attach Mechanism

5.7 Socket and Voltage Regulation Cooling Strategy

Intel® Quiet System Technology (Intel® QST)

6.1 Intel® Quiet System Technology Algorithm

6.1.1 Output Weighting Matrix

6.1.2 Proportional-Integral-Derivative (PID)

6.3 Intel® QST Configuration & Tuning

6.4 Fan Hub Thermistor and Intel® QST