Dell U2421E User Manual

Dell UltraSharp 24
USB-C Hub Monitor - U2421E

User’s Guide

Model: U2421E
Regulatory model: U2421Et

NOTE: A NOTE indicates important information that helps you make
better use of your computer.

CAUTION: A CAUTION indicates potential damage to hardware or loss of
data if instructions are not followed.

WARNING: A WARNING indicates a potential for property damage,
personal injury, or death.

Copyright © 2020 Dell Inc. or its subsidiaries. All rights reserved. Dell, EMC, and other trademarks

are trademarks of Dell Inc. or its subsidiaries. Other trademarks may be trademarks of their respective
owners.

2020 – 10

Rev. A00

Contents

Safety instructions..............................5

About your monitor .............................6

Package contents . . . . . . . . . . . . . . . . . . . . . . . . . 6

Product features. . . . . . . . . . . . . . . . . . . . . . . . . .7

Identifying parts and controls. . . . . . . . . . . . . . . . . . .8

Front view. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Back view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Bottom view . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Monitor specifications. . . . . . . . . . . . . . . . . . . . . . .11

Resolution specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Preset display modes. . . . . . . . . . . . . . . . . . . . . . . . . . . . .13

DP MST Multi-Stream Transport (MST) Modes . . . . . . . . . . . . . . 13

USB-C MST Multi-Stream Transport (MST) Modes . . . . . . . . . . . . 13

Electrical specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Physical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Environmental characteristics . . . . . . . . . . . . . . . . . . . . . . . . 16

Pin assignments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Plug-and-Play . . . . . . . . . . . . . . . . . . . . . . . . . . 24

LCD monitor quality and pixel policy . . . . . . . . . . . . . . 24

Ergonomics . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Handling and moving your display. . . . . . . . . . . . . . . . 27

Maintenance guidelines . . . . . . . . . . . . . . . . . . . . . 28

Cleaning your monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

Setting up the monitor..........................29

Connecting the stand . . . . . . . . . . . . . . . . . . . . . . 29

Using the tilt, swivel, and vertical extension . . . . . . . . . . 32

Contents | 3

Tilt, swivel and vertical extension . . . . . . . . . . . . . . . . . . . . . .32

Rotating the Display . . . . . . . . . . . . . . . . . . . . . . . 32

Configuring the display settings on your computer after rotation 33

Connecting your monitor . . . . . . . . . . . . . . . . . . . . 34

Organizing your cables . . . . . . . . . . . . . . . . . . . . . 38

Securing your monitor using Kensington lock (optional) . . . 38

Removing the monitor stand . . . . . . . . . . . . . . . . . . 39

Wall mounting (Optional) . . . . . . . . . . . . . . . . . . . . 40

Operating the monitor ..........................41

Power on the monitor . . . . . . . . . . . . . . . . . . . . . . 41

Using the joystick control . . . . . . . . . . . . . . . . . . . . 41

Using the rear-panel controls . . . . . . . . . . . . . . . . . . 42

Using the OSD lock function . . . . . . . . . . . . . . . . . . 43

Front-panel button . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Using the On-Screen Display (OSD) Menu . . . . . . . . . . . 47

Accessing the menu system . . . . . . . . . . . . . . . . . . . . . . . . .47

OSD warning messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Setting the maximum resolution. . . . . . . . . . . . . . . . . . . . . . .61

Troubleshooting ...............................62

Self-test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Built-in diagnostics . . . . . . . . . . . . . . . . . . . . . . . 63

Common Problems. . . . . . . . . . . . . . . . . . . . . . . . 64

Product specific problems . . . . . . . . . . . . . . . . . . . 65

Universal Serial Bus (USB) specific problems . . . . . . . . . 68

Appendix.....................................70

FCC notices (U.S. only) and other regulatory information . . . 70

Contacting Dell . . . . . . . . . . . . . . . . . . . . . . . . . 70

EU product database for energy label and product information

sheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

4 | Contents

Safety instructions

WARNING: Use of controls, adjustments, or procedures other than those

specified in this documentation may result in exposure to shock, electrical
hazards, and/or mechanical hazards.

• Place the monitor on a solid surface and handle it carefully. The screen is fragile
and can be damaged if dropped or hit sharply.

• Always be sure that your monitor is electrically rated to operate with the AC
power available in your location.

• Keep the monitor in room temperature. Excessive cold or hot conditions can have
an adverse effect on the liquid crystal of the display.

• Do not subject the monitor to severe vibration or high impact conditions. For
example, do not place the monitor inside a car trunk.

• Unplug the monitor when it is going to be left unused for an extended period of
time.

• To avoid electric shock, do not attempt to remove any cover or touch the inside
of the monitor.

For information on safety instructions, see the Safety, Environmental, and Regulatory
Information (SERI).

Safety instructions | 5

About your monitor

Package contents

Your monitor ships with the components shown in the table below. If any component is
missing, contact Dell. For more information, see Contact Dell.

NOTE: Some components may be optional and may not ship with your

monitor. Somefeatures may not be available in certain countries.

Display

Stand riser

6 | About your monitor

Stand base

Power cable (varies by country)

DisplayPort cable (DisplayPort to
DisplayPort)

USB Type-C cable (C to A)

USB Type-C cable (C to C)

Dell UltraSharp U2421E

2020-09

U2421E Color Calibration Factory Report

Every Dell U2421E is shipped incorporating pre-tuned

Serial No.

CN00WG2J7444572B046L
standard mode(sRGB) with average Delta-E ≤2.
This helps prevent significant color inconsistency or

Tester

2008L0415
inaccuracy when content is displayed onscreen.
In addition, a tighter grey-scale tracking on each U2421E
helps enable ultra-smooth color gradation. The factory
measurements from this very unit are shown here.

Test

CA-210/CA-310

CA-2000S

Equipment

Be assured of Accurate, Precise and Consistent

Chroma 2326/2235/2233

Onscreen Color with eve

ry Dell UltraSharp U2421E.

Standard mode (sRGB) Avg. Delta E ≤ 2

Gray-Scale Tracking

Dell.com/U2421E

Gamma

Note:
Calibrations were done according to Dell approved test procedures using calib rated
equipment at the factory production line. This Report is provided only with and for this new Dell U2421E
UltraSharp monitor. Results may vary with other test equipment, setups and test p atterns. Pleas e retain this Re port
for your reference as Dell is unable to reproduce it or provide a duplicate.

• Quick Setup Guide

• Safety, Environmental, and Regulatory
Information

• Factory Calibration Report

Product features

The Dell UltraSharp U2421E monitor has an active matrix, Thin-Film Transistor
(TFT), Liquid Crystal Display (LCD), and LED backlight. The monitor features include:

• 61.13 cm (24.1 in.) active area display (Measured diagonally) 1920 x 1200 (16:10)
resolution, plus full-screen support for lower resolutions.

• Wide viewing angles with 99% sRGB color with an average Delta E<2.

• Tilt, swivel, pivot and vertical extension adjustment capabilities.

• Removable pedestal stand and Video Electronics Standards Association (VESA™)
100 mm mounting holes for flexible mounting solutions.

• Ultra-thin bezel minimizes the bezel gap during multi-monitor usage, enabling
easier set up with an elegant viewing experience.

• Extensive digital connectivity with DP helps future-proof your monitor.

• Single USB Type-C to supply power to compatible notebook while receiving video
signal.

• USB-C and RJ45 ports enable a single-cable, network-connected experience.

• Plug and play capability if supported by your computer.

• On-Screen Display (OSD) adjustments for ease of set-up and screen
optimization.

• Power and OSD buttons lock.

• Security lock slot.

• ≤ 0.3 W in Standby Mode.

• Premium Panel Exchange for peace of mind.

• Optimize eye comfort with a flicker-free screen minimizes hazard blue light
emission.

• The Monitor use Low Blue Light panel and compliance with TUV Rheinland
(Hardware Solution) at factory reset/default setting model.

• Decreases the level of hazard blue light emitted from the screen to make viewing
more comfortable for your eyes.

WARNING: The possible long-term effects of blue light emission from the

monitor may cause damage to the eyes, including eye fatigue or digital eye
strain.

About your monitor | 7

Identifying parts and controls

Front view

Label Description Use
1 Power LED indicator Solid white light indicates

the monitor is turned on and
functioning normally. Blinking white
light indicates the monitor is in
Standby Mode.

1

8 | About your monitor

Back view

7

1
2

3

654

Label Description Use

1 VESA mounting holes (100 mm

x 100 mm-behind attached
VESA cover)

2 Regulatory label Lists the regulatory approvals.

3 Stand release button Releases stand from the monitor.

4 Power On/Off button To turn the monitor on or off.

5 Joystick Use it to control the OSD menu.

6 Mac address, Barcode, serial

number, and Service Tag label

7 Cable-management slot Use to organize cables by inserting them

Wall mount monitor using VESA­compatible wall mount kit (100 mm x 100
mm).

For more information, see Operating the

Monitor.

Refer to this label if you need to contact Dell
for technical support. The Service Tag is a
unique alphanumeric identifier that enables
Dell service technicians to identify the
hardware components in your computer and
access warranty information.

through the slot.

About your monitor | 9

Bottom view

99

13

1 4 5 6 7 8

Label Description Use

1 Security lock slot Secures monitor with security cable lock (sold separately).

2 Power connector Connect the power cable.

3 HDMI port Connect your computer with the HDMI cable.

4 DisplayPort in Connect your computer with the DisplayPort cable.

5 USB Type-C/

DisplayPort

6 DP port (out) DP output for MST (multi-stream transport) capable

7,9,1 1 SuperSpeed USB

5 Gbps (USB 3.2
Gen1) (3)

8 Audio line-out

port

32 11 129 10

Connect to your computer using the USB Type-C cable.
The USB Type-C port offer the fastest transfer rate and
the alternate mode with DP 1.4 support the maximum
resolution of 1920 x 1200 at 60 Hz PD 20 V/4.5 A, 15 V/3 A,
9 V/3 A, 5 V/3 A.
NOTE: USB Type-C is not supported on Windows versions
that are prior to Windows 10.

monitor. To enable MST, refer to instruction on section
“Connecting the Monitor for DP MST Function”.
NOTE: Remove the rubber plug when using DP out
connector.

Connect your USB device. You can use these ports only
after you have connected the USB cable (Type-A to
Type-C or Type-C to Type-C) from the computer to the
monitor. Port with battery icon supports Battery
Charging Rev. 1.2.

Connect speakers to playback audio through HDMI or
DisplayPort audio channels.
Only two-channel audio is supported.
NOTE: The audio line-out port does not support
headphones.

10 | About your monitor

10 RJ-45 connector Connect Internet. You can surf Internet via RJ45 only after

you have connected the USB cable(Type-A to Type-C or
Type-C to Type-C) from the computer to the monitor.

12 USB Type-C

downstream port

13 Stand lock Lock the stand to the monitor using a M3 x 8 mm screw

Port with icon supports 5 V/ 3 A.
Connect your USB device. You can use these ports only
after you have connected the USB cable (Type-A to
Type-C or Type-C to Type-C) from the computer to the
monitor.

(screw not included).

Monitor specifications

Screen type Active matrix - TFT LCD

Panel Type In-plane switching Technology

Aspect ratio 16:10

Viewable image dimensions

Diagonal 61.13 cm (24.1 in.)

Active Area

Horizontal 518.4 mm (20.40 in.)

Vertical 324.0 mm (12.76 in.)

Area 167961.6 mm2 (260.30 in.2)

Pixel pitch 0.27 mm x 0.27 mm

Pixel per inch (PPI) 93.95

Viewing angle
Horizontal 178° (typical)
Vertical 178° (typical)
Brightness 350 cd/m² (typical)

Contrast ratio 1000 to 1 (typical)

Display screen coating Anti-glare treatment of the front polarizer (3H) hard

coating

Backlight LED

Response Time (Gray to
Gray)

Color depth 16.78 million colors

5 ms (Fast mode)
8 ms (Normal mode)

About your monitor | 11

Color gamut* 99% sRGB

99% REC709

Calibration accuracy Delta E < 2 (average)

Connectivity • 1 x DP 1.4

• 1 x HDMI1 .4

• 1 x USB Type-C (Alternate mode with DisplayPort 1.4,
USB 3.2 Gen 1 upstream port, Power Delivery PD up
to 90 W)

• 1 x USB Type-C downstream (15 W), USB 3.2 Gen 1 (5
Gbps)

• 1 x DP (Out) with MST

• 2 x SuperSpeed USB 5 Gbps (USB 3.2 Gen 1)

• 1 x SuperSpeed USB 5 Gbps (USB 3.2 Gen 1) with BC

1.2 charging capability at 2 A (max)

• 1 x Analog 2.0 audio line out (3.5 mm jack)

• 1 x RJ45

Border width (edge of monitor to active area)

To p

Left/Right

Bottom

Adjustability

Height adjustable stand 150 mm

Tilt -5° to 21°

Swivel -45° to 45°

Pivot -90° to 90°

Cable management Yes

Dell Display Manager (DDM)
Compatibility

Security Security lock slot (cable lock sold separately)

6.2 mm

6.2 mm

9.1 mm

Easy Arrange
and other key features

* At panel native only, under Custom Mode preset.

Resolution specifications

Horizontal scan range 30 kHz to 83 kHz

Vertical scan range 49 Hz to 76 Hz

12 | About your monitor

Maximum preset resolution 1920 x 1200 at 60 Hz

(kHz)

(Hz)

(MHz)

Vertical)

VGA 720 x 400

31.47

70

28.322

-/+

VESA 640 x 480

37.57531.5

-/-

VESA 800 x 600

37.8 8

6040+/+

VESA 800 x 600

46.88

75

49.5

+/+

VESA 1024 x 768

48.36

6065-/-

VESA 1024 x 768

60.02

75

78.75

+/+

MAC 1152 x 864

67.575108

+/+

VESA 1280 x 1024

6460108

+/+

VESA 1280 x 1024

8075135

+/+

CVT 1600 x 900

55.99

60

118.25

+/+

CVT 1920 x 1080

67.560148.5

+/+

Video display capabilities (HDMI & DP & USB
Type-C alternate mode)

480i, 480p, 576i, 560p, 720p, 1080i,
1080p

Preset display modes

Display mode Horizontal

frequency

Vertical
frequency

Pixel
clock

VGA 640 x 480 31.47 60 25.175 -/-

CVT 1920 x 1200 74.04 60 154 + /+

Sync polarity
(Horizontal/

DP MST Multi-Stream Transport (MST) Modes

MST Source Monitor Maximum number of external monitors that can be

supported
1920 x 1200/60 Hz

1920 x 1200/60 Hz 2

NOTE: Maximum external monitor resolution supported is 1920 x 1200 60 Hz only.

USB-C MST Multi-Stream Transport (MST) Modes

OSD Dislay Info: Link rate(current) Maximum number of external monitors that can be

supported

1920 x 1200/60 Hz

About your monitor | 13

HBR3 2

HBR2 1

Electrical specifications

Video input signals • Digital video signal for each dierential line

Per dierential line at 100 ohm impedance

• DP/HDMI/USB Type-C signal input support

Input voltage/ frequency/current 100-240 VAC / 50 or 60 Hz ± 3 Hz / 2.1 A

(maximum)

Inrush current 120 V: 42 A (Max.)

240 V: 80 A (Max.)

Inrush current is measured at an ambient
temperature of 0°C.

Power Consumption 0.2 W (Off Mode)

0.2 W (Standby Mode)

17.2 W (On Mode)

186 W (Max)

16.16 W (Pon)

52.39 kWh (TEC)

1

As dened in EU 2019/2021 and EU 2019/2013.

2

Max brightness and contrast setting with maximum power loading on all USB ports.

3

Pon: Power consumption of On Mode as dened in Energy Star 8.0 version.

1

1

1

2

3

3

TEC: Total energy consumption in kWh as dened in Energy star 8.0 version.

This document is informational only and reects laboratory performance. Your prod­uct may perform dierently, depending on the software, components and peripherals
you ordered and shall have no obligation to update such information. Accordingly, the
customer should not rely upon this information in making decisions about electrical
tolerances or otherwise. No warranty as to accuracy or completeness is expressed or
implied.

NOTE: This monitor is ENERGY STAR certied.

This product qualies for ENERGY STAR in the factory default settings which can be
restored by “Factory Reset” function in the OSD menu. Changing the factory default
settings or enabling other features may increase power consumption that could exceed

the ENERGY STAR specied limit.

14 | About your monitor

Physical characteristics

Connector type • DP connector (include DP in and DP out)

• HDMI connector

• USB Type-C connector

• Audio line-out

• RJ45 connector

• USB Type-C downstream connector x 1

(Port with icon supports 5 V/3 A)

• USB 3.2 Gen 1 downstream port connector x 3

(Port with battery icon supports BC 1.2.)

Signal cable type DP to DP 1.8 M cable

USB Type-C (C to C) 1.0 M cable
USB Type-C (C to A) 1.8 M cable

Dimensions (with stand)

Height (extended) 510.7 mm (20.11 in.)

Height (compressed) 364.0 mm (14.33 in.)

Width 530.8 mm (20.90 in.)

Depth 173.0 mm (6.81 in.)

Dimensions (without stand)

Height 339.3 mm (13.36 in.)

Width 530.8 mm (20.90 in.)

Depth 50.0 mm (1.97 in.)

Stand dimensions

Height (extended) 410.8 mm (16.17 in.)

Height (compressed) 364.0 mm (14.33 in.)

Width 244.9 mm (9.64 in.)

Depth 173.0 mm (6.81 in.)

Weight

Weight with packaging 8.6 kg (19.0 lb)

Weight with stand assembly and
cables

6.1 kg (13.4 lb)

About your monitor | 15

Weight without stand assembly
(For wall mount or VESA mount
considerations - no cables)

Weight of stand assembly 1.7 kg (3.7 lb)

Environmental characteristics

Compliant Standards

• ENERGY STAR certified Monitor.

• EPEAT registered where applicable. EPEAT registration varies by country.
See www.epeat.net for registration status by country.

• TCO Certified Display.

• RoHS Compliant.

• BFR/PVC Free monitor (excluding external cables).

• Meets NFPA 99 leakage current requirements.

• Arsenic-Free glass and Mercury-Free for the panel only.
Temperature

Operating 0°C to 40°C (32°F to 104°F)
Non-operating –20°C to 60°C (–4°F to 140°F)

Humidity

Operating 10% to 80% (non-condensing)
Non-operating 5% to 90% (non-condensing)

Altitude
Operating 5,000 m (16,404 ft) (maximum)
Non-operating 12,192 m (40,000 ft) (maximum)
Thermal dissipation 635.0 BTU/hour (Maximum)

4.0 kg (8.8 lb)

58.72 BTU/hour (On mode)

16 | About your monitor

Pin assignments

DP port (in)

Pin number 20-pin side of theconnected signal cable

1 ML3(n)

2 GND

3 ML3(p)

4 ML2(n)

5 GND

6 ML2(p)

7 ML1(n)

8 GND

9 ML1(p)

10 ML0(n)

11 GND

12 ML0(p)

13 CONFIG1

14 CONFIG2

15 AUX CH (p)

16 GND

17 AUX CH (n)

18 Hot Plug Detect

19 Return

20 DP_PWR

About your monitor | 17

DP port (out)

Pin number 20-pin side of theconnected signal cable

1 ML0(p)

2 GND

3 ML0(n)

4 ML1(p)

5 GND

6 ML1(n)

7 ML2(p)

8 GND

9 ML2(n)

10 ML3(p)

11 GND

12 ML3(n)

13 CONFIG1

14 CONFIG2

15 AUX CH(p)

16 GND

17 AUX CH(n)

18 Hot Plug Detect

19 Return

20 DP_PWR

18 | About your monitor

HDMI port

Pin number 19-pin side of theconnected signal cable

1 TMDS DATA 2+

2 TMDS DATA 2 SHIELD

3 TMDS DATA 2-

4 TMDS DATA 1+

5 TMDS DATA 1 SHIELD

6 TMDS DATA 1-

7 TMDS DATA 0+

8 TMDS DATA 0 SHIELD

9 TMDS DATA 0-

10 TMDS CLOCK+

11 TMDS CLOCK SHIELD

12 TMDS CLOCK-

13 CEC

14 Reserved (N.C. on device)

15 DDC CLOCK (SCL)

16 DDC DATA (SDA)

17 DDC/CEC Ground

18 +5 V POWER

19 HOT PLUG DETECT

About your monitor | 19

USB Type-C port

Pin Signal Pin Signal

A1 GND B12 GND

A2 SSTXp1 B11 SSRXp1

A3 SSTXn1 B10 SSRXn1

A4 VBUS B9 VBUS

A5 CC1 B8 SBU2

A6 Dp1 B7 Dn1

A7 Dn1 B6 Dp1

A8 SBU1 B5 CC2

A9 VBUS B4 VBUS

A10 SSRXn2 B3 SSTXn2

A11 SSRXp2 B2 SSTXp2

A12 GND B1 GND

20 | About your monitor

Universal Serial Bus (USB)

This section gives you information about the USB ports available on your monitor.

NOTE: Up to 2 A on USB downstream port (port with battery icon) with

BC 1.2 compliance devices; up to 0.9 A on the other 2 USB downstream ports;
Up to 3 A on USB Type-C downstream port (port with icon) with 5 V/3 A
compliance devices.

Your computer has the following USB ports:

• 4 downstream - 2 at quick access, 2 at rear
Power Charging Port - the ports with battery icon supports fast current
charging capability if the device is BC 1.2 compatible.The USB Type-C downstream
port with icon supports fast current charging capability if the device is 5V/3A
compatible.

NOTE: The monitor’s USB ports work only when the monitor is on or in the power

save mode. In power save mode, if the USB cable (Type-C to Type-C) is plugged
in, the USB ports can work normally. Otherwise, follow the OSD setting of USB,
if the setting is “On During Standby” then USB work normally, otherwise USB is
disabled. If you turn off the monitor and then turn it on, the attached peripherals
may take a few seconds to resume normal functionality.

Transfer speed Data rate Maximum power consumption (each port)

SuperSpeed 5 Gbps 4.5 W
Hi-Speed 480 Mbps 2.5 W
Full speed 12 Mbps 2.5 W

USB downstreamport

Pin number Signal Pin number Signal

1

2

3

4

5

VBUS

D-

D+

GND

StdA_SSRX-

6

7

8

9

Shell

StdA_SSRX+

GND_DRAIN

StdA_SSTX-

StdA_SSTX+

Shield

About your monitor | 21

RJ45 port (connector side)

PHY SIDE

CABLE SIDE

RJ45

GREEN

GREEN

ORANGE

SHIELD

GROUND

2kV, 1000pF

Pin Signal Pin Signal

1 TD1 + 8 TD3 -

2 TD1 - 9 TD4 +

3 TD2 + 10 TD4 -

4 TD2 - 11 GREEN_OR-

ANGE

5 CT 12 GREEN_OR-

ANGE

6 CT 13 GREEN

7 TD3 + 14 GREEN

Driver installation

Install the Realtek USB GBE Ethernet Controller Driver available for your system. This
is available for download at www.dell.com/support under the “Driver and download”
section.

Network (RJ45) data rate via USB-C max speed is 1000 Mbps.

NOTE: This LAN port is 1000Base-T IEEE 802.3az compliant, supporting Mac

Address (Printed on model label) Pass-thru, Wake-on-LAN (WOL) from standby
mode (S3 only) and PXE Boot function, these 3 features depend on BIOS setting
and OS version.

22 | About your monitor

RJ45 Connector LED status:

LED Color Description

Right LED Amber or Green Speed indicator:

• Amber On - 1000 Mbps

• Green On - 100 Mbps

• Off - 10 Mbps

Right LED
Left LED

Left LED Green Link / Activity indicator:

• Blinking - Activity on the port.

• Green On - Link is being established.

• Off - Link is not established.

NOTE: RJ45 cable is non in-box standard accessory.

About your monitor | 23

Plug-and-Play

You can install the monitor in any Plug-and-Play-compatible system. The monitor
automatically provides the computer system with its extended display identification
data (EDID) using display data channel (DDC) protocols so the computer can configure
itself and optimize the monitor settings. Most monitor installations are automatic;
you can select different settings if desired. For more information about changing the
monitor settings, see Operating the Monitor.

LCD monitor quality and pixel policy

During the LCD monitor manufacturing process, it is not uncommon for one or more
pixels to become fixed in an unchanging state which are hard to see and do not affect
the display quality or usability. For more information on LCD Monitor Pixel Policy, see
Dell support site at: www.dell.com/pixelguidelines.

24 | About your monitor

Ergonomics

CAUTION: Improper or prolonged usage of keyboard may result in injury.

CAUTION: Viewing the monitor screen for extended periods of time may

result in eye strain.

For comfort and efficiency, observe the following guidelines when setting up and using
your computer workstation:

• Position your computer so that the monitor and keyboard are directly in front of

you as you work. Special shelves are commercially available to help you correctly
position your keyboard.

• To reduce the risk of eye strain and neck/arm/back/shoulder pain from using the

monitor for long periods of time, we suggest you to:

1. Set the distance of the screen between 20 to 28 in. (50 - 70 cm) from your
eyes.

2. Blink frequently to moisten your eyes or wet your eyes with water after
prolonged usage of the monitor.

3. Take regular and frequent breaks for 20 minutes every two hours.

4. Look away from your monitor and gaze at a distant object at 20 feet away for
at least 20 seconds during the breaks.

5. Perform stretches to relieve tension in the neck, arm, back, and shoulders
during the breaks.

• Make sure that the monitor screen is at eye level or slightly lower when you are
sitting in front of the monitor.

• Adjust the tilt of the monitor, its contrast, and brightness settings.

• Adjust the ambient lighting around you (such as overhead lights, desk lamps, and
the curtains or blinds on nearby windows) to minimize reflections and glare on the
monitor screen.

• Use a chair that provides good lower-back support.

• Keep your forearms horizontal with your wrists in a neutral, comfortable position
while using the keyboard or mouse.

• Always leave space to rest your hands while using the keyboard or mouse.

• Let your upper arms rest naturally on both sides.

• Ensure that your feet are resting flat on the floor.

• When sitting, make sure that the weight of your legs is on your feet and not
on the front portion of your seat. Adjust your chair’s height or use a footrest if
necessary to maintain a proper posture.

About your monitor | 25

• Vary your work activities. Try to organize your work so that you do not have to sit
and work for extended periods of time. Try to stand or get up and walk around at
regular intervals.

• Keep the area under your desk clear of obstructions and cables or power cords
that may interfere with comfortable seating or present a potential trip hazard.

monitor screen at or
below eye level

monitor and
keyboard
positioned
directly in front
of the user

wrists relaxed
and at

feet at on the
oor

26 | About your monitor

Handling and moving your display

To ensure the monitor is handled safely when lifting or moving it, follow the guidelines
mentioned below:

• Before moving or lifting the monitor, turn off your computer and the monitor.

• Disconnect all cables from the monitor.

• Place the monitor in the original box with the original packing materials.

• Hold the bottom edge and the side of the monitor firmly without applying
excessive pressure when lifting or moving the monitor.

• When lifting or moving the monitor, ensure the screen is facing away from you
and do not press on the display area to avoid any scratches or damage.

• When transporting the monitor, avoid any sudden shock or vibration to it.

About your monitor | 27

• When lifting or moving the monitor, do not turn the monitor upside down while
holding the stand base or stand riser. This may result in accidental damage to the
monitor or cause personal injury.

Maintenance guidelines

Cleaning your monitor

WARNING: Before cleaning the monitor, unplug the monitor power cable

from the electrical outlet.

CAUTION: Read and follow the Safety Instructions before cleaning the

monitor.

For best practices, follow these instructions in the list below while unpacking, cleaning,
or handling your monitor:

• To clean your anti-static screen, lightly dampen a soft, clean cloth with water. If
possible, use a special screen-cleaning tissue or solution suitable for the anti­static coating. Do not use benzene, thinner, ammonia, abrasive cleaners, or
compressed air.

• Use a lightly-dampened, soft cloth to clean the monitor. Avoid using detergent of
any kind as some detergents leave a milky film on the monitor.

• If you notice white powder when you unpack your monitor, wipe it off with a
cloth.

• Handle your monitor with care as a darker-colored monitor may get scratched
and show white scuff marks more than a lighter- colored monitor.

• To help maintain the best image quality on your monitor, use a dynamically
changing screen saver and turn off your monitor when not in use.

28 | About your monitor

Setting up the monitor

Connecting the stand

NOTE: The stand riser and stand base are detached when the monitor is

shipped from the factory.

NOTE: The following instructions are applicable only for the stand that

was shipped with your monitor. If you are connecting a stand that you
purchased from any other source, follow the set up instructions that were
included with the stand.

To attach the monitor stand:

1. Align and place the stand riser on the stand base.

2. Open the screw handle at the bottom of the stand base and turn it clockwise to

secure the stand assembly.

3. Close the screw handle.

1

3

2

Setting up the monitor | 29

4. Open the protective cover on the monitor to access the VESA slot on the

monitor.

5. Slide the tabs on the stand riser into the slots on the display back cover and
lower the stand assembly to snap it into place.

30 | Setting up the monitor

6. Hold the stand riser and lift the monitor carefully, then place it on a at surface.

NOTE: Hold the stand riser firmly when lifting the monitor to avoid any

accidental damage.

7. Lift the protective cover from the monitor.

Setting up the monitor | 31

Using the tilt, swivel, and vertical extension

5°

45

°

NOTE: The following instructions are applicable only for the stand that

was shipped with your monitor. If you are connecting a stand that you
purchased from any other source, follow the set up instructions that were
included with the stand.

Tilt, swivel and vertical extension

With the stand attached to the monitor, you can tilt the monitor for the most
comfortable viewing angle.

°

150 mm

21°

45

NOTE: The stand is detached when the monitor is shipped from the

factory.

Rotating the Display

Before you rotate the display, extend the display vertically until the top of the stand
riser and then tilt the display backwards until the maximum to avoid hitting the bottom
edge of the display.

1

2

90°

90°

32 | Setting up the monitor

NOTE: To toggle the display setting on your Dell computer between landscape and

portrait when rotating the display, download and install the latest graphics driver.
To download, go to www.dell.com/support/drivers and search for the appropriate
driver.

NOTE: When the display is in portrait mode, you may experience performance

degradation when using graphic-intensive applications such as 3D gaming.

Configuring the display settings on your computer after rotation

After you have rotated the display, complete the procedure given below to configure
the display settings on your computer.

NOTE: If you are using the monitor with a non-Dell computer, go to the graphics

card manufacturer’s website or your computer manufacturer website for
information on how to rotate the contents of your display.

To configure the Display Settings:

1. Right-click on the Desktop and click Properties.

2. Select the Settings tab and click Advanced.

3. If you have an AMD graphics card, select the Rotation tab and set the

preferred rotation.

4. If you have an nVidia graphics card, click the nVidia tab, in the left-hand
column select NVRotate, and then select the preferred rotation.

5. If you have an Intel® graphics card, select the Intel graphics tab, click Graphic
Properties, select the Rotation tab, and then set the preferred rotation.

NOTE: If you do not see the rotation option or it is not working correctly, go to

www.dell.com/support and download the latest driver for your graphics card.

Setting up the monitor | 33

Connecting your monitor

WARNING: Before you begin any of the procedures in this section, follow

the Safety Instructions.

To connect your monitor to the computer:

1. Turn o your computer.

2. Connect the DisplayPort or HDMI cable, and the USB Type-C cable from your

monitor to the computer.

3. Turn on your monitor.

4. Select the correct input source from the OSD Menu on your monitor and then

turn on your computer.

NOTE: U2421E default setting is DisplayPort 1.4. A DisplayPort 1.1 Graphic

card may not display normally. Please refer to “product specific problems

– No image when using DP connection to the PC” to change default

setting.

Connecting the HDMI cable (Optional)

HDMI

HDMI

34 | Setting up the monitor

Connecting the DP cable

DP

DP

Connecting the monitor for DP Multi-Stream Transport (MST) function

DP

DP out

DP

DP

NOTE: Supports the DP MST feature. To make use of this feature, your PC

Graphics Card must be certified to at least DP1.2 with MST option.

NOTE: Remove the rubber plug when using DP out connector.

Setting up the monitor | 35

Connecting the USB cable

USB

Connecting the USB Type-C cable

USB Type-C

USB

USB Type-C

The USB Type-C port on your monitor:

• Can be used as USB Type-C or DisplayPort 1.4, alternatively.

• Supports USB Power Delivery (PD), with profiles up to 90 W.

NOTE: Regardless of the power requirement/actual power consumption

of your laptop, or the remaining power runtime in your battery, the Dell
U2421E monitor is designed to supply power delivery of up to 90 W to
your laptop.

Rated power (on laptops that have
USB Type-C with PowerDelivery)

Maximum charging
power

45 W 45 W

65 W 65 W

90 W 90 W

130 W Not supported

36 | Setting up the monitor

Connecting the monitor for USB-C Multi-Stream Transport (MST) function

USB Type-C

DP in

DP out

USB Type-C

NOTE: The maximum number of supported U2421E via MST is subjected to the

bandwith of the USB-C source. Please refer to “product specific problems –

No image when using USB Type-C MST”.

NOTE: Remove the rubber plug when using DP out connector.

Connecting the monitor for RJ45 Cable (Optional)

USB Type-C

RJ45

USB Type-C

Setting up the monitor | 37

Organizing your cables

After attaching all necessary cables to your monitor and computer, (see Connecting

Your Monitor for cable attachment) organize all cables as shown above.

Securing your monitor using Kensington lock (optional)

The security lock slot is located at the bottom of the monitor. (See Security lock

slot)

For more information on using the Kensington lock (purchased separately), see the
documentation that is shipped with the lock.

Secure your monitor to a table using the Kensington security lock.

NOTE: The image is for the purpose of illustration only. Appearance of the

lock may vary.

38 | Setting up the monitor

Removing the monitor stand

CAUTION: To prevent scratches on the LCD screen when removing the

stand,ensure that the monitor is placed on a soft, clean surface.

NOTE: The following instructions are applicable only for the stand that

was shipped with your monitor. If you are connecting a stand that you
purchased from any other source, follow the set up instructions that were

included with the stand.

To remove the stand:

1. Place the monitor on a soft cloth or cushion.

2. Press and hold the stand-release button.

3. Lift the stand up and away from the monitor.

3

2

Setting up the monitor | 39

Wall mounting (Optional)

NOTE: Use M4 x 10 mm screws to connect the monitor to the wall-

mounting kit.

Refer to the instructions that come with the VESA-compatible wall mounting kit.

1. Place the monitor on a soft cloth or cushion on a stable flat table.

2. Remove the stand.

3. Use a Phillips crosshead screwdriver to remove the four screws securing the

plastic cover.

4. Attach the mounting bracket from the wall mounting kit to the monitor.

5. Mount the monitor on the wall as instructed in the documentation that shipped

with the wall-mounting kit.

NOTE: For use only with UL or CSA or GS-listed wall mount bracket with

minimum weight/load bearing capacity of 16 kg (35.2 lb).

40 | Setting up the monitor

Operating the monitor

Power on the monitor

Press the button to turn on the monitor.

Using the joystick control

Use the joystick control on the rear of the monitor to make OSD adjustments.

1. Press the joystick button to launch the OSD main menu.

2. Move the joystick up/down/left/right to toggle between options.

3. Press the joystick button again to confirm the settings and exit.

Joystick Description

• When the OSD menu is on, press the button to confirm the selection
or save the settings.

• When the OSD menu is off, press the button to launch the OSD main
menu. See Accessing the menu system.

• For 2-way (right and left) directional navigation.

• Move right to enter the submenu.

• Move left to exit from the submenu.

• Increases (right) or decreases (left) the parameters of selected menu
item.

• For 2-way (up and down) directional navigation.

• Toggles between the menu items.

• Increases (up) or decreases (down) the parameters of selected menu
item.

Operating the monitor | 41

Using the rear-panel controls

Use the joystick control on the rear of the monitor to adjust the display settings. As
you use the button to adjust the settings, an OSD shows the numeric values of each
feature as they change.

Display Info

The following table describes the rear-panel buttons:

Options Description
1

Use this Menu button to launch the on-screen
display (OSD) and select the OSD menu.

Menu

2

See Accessing the menu system

Use this button to choose from a list of Display

Info.

Display Info

3

Use this button to choose from a list of Input
Source.

Input Source

4

Use this button to choose from a list of preset
colormodes.

Preset Modes

5

Brightness/Contrast

6

Aspect Ratio

7

Exit

42 | Operating the monitor

To directly access the Brightness/Contrast
adjustment sliders.

Use this button to choose from a list of Aspect
Ratio.

Use this button to go back to the main menu or

exit the OSD main menu.

Using the OSD lock function

You can lock the front-panel control buttons to prevent access to the OSD menu and/
or power button.

Use the Lock menu to lock the button(s).

1. Select one of the following options.

2. The following message appears.

3. Select Yes to lock buttons. Once locked, pressing any control button will display

the lock icon .

Operating the monitor | 43

Use the Joystick to lock the button(s).

Press the left directional navigation of Joystick for four seconds, a menu appears on
the screen.

Select one of the following options:

Options Description

1

Select this option to lock OSD menu function.

Menu Button lock

2

Power Button lock

3

Menu and Power Button lock

4

Built-in Diagnostics

44 | Operating the monitor

Use this option to lock power button. This will
prevent the user to turn off the monitor using the
power button.

Use this option to lock OSD menu and power
button to turn off the monitor.

Use this option to run the built-in diagnostics, see

Built-in Diagnostics.

To unlock the button(s).

Press the left directional navigation of Joystick for four seconds until a menu appears
on the screen. The following table describes the options to unlock the front-panel
control buttons.

Options Description

1

Menu Button unlock

2

Use this option to unlock OSD menu function.

Use this option to unlock power button to turn off
the monitor.

Power Button unlock

3

Menu and Power Button

unlock

Use this option to unlock OSD menu and power
button to turn off the monitor.

Operating the monitor | 45

Front-panel button

Use the buttons on the front of the monitor to adjust the image settings.

Front Panel Description

1

Up Down

2

Previous

3

Use the Up (increase) and Down (decrease) buttons to
adjust items in the OSD menu.

Use the Previous button to go back to the previous
menu.

Use the Next button to confirm your selection.

Next

4

Tick

Use the Tick button to confirm your selection.

46 | Operating the monitor

Using the On-Screen Display (OSD) Menu

Accessing the menu system

Icon Menu and

Submenus

Brightness/
Contrast

Brightness Brightness adjusts the luminance of the backlight

Contrast Adjust the Brightness first, and then adjust Contrast only

Description

Use this menu to activate Brightness/Contrast adjustment.

(minimum 0; maximum 100).

Move the joystick up to increase brightness.
Move the joystick down to decrease brightness.

if further adjustment is necessary.
Move the joystick up to increase contrast and Move the
joystick down to decrease contrast (between 0 and 100).

The Contrast function adjusts the degree of difference
between darkness and lightness on the monitor screen.

Operating the monitor | 47

Icon Menu and

Submenus

Input Source Use the Input Source menu to select between different

Description

video inputs that are connected to your monitor.

USB-C
90 W

DP Select DP input when you are using the DP (DisplayPort)

HDMI Select the HDMI input when you are using the HDMI

Auto Select Turn on the function to allow the monitor to automatically

Auto Select
for USB-C

Rename Inputs Allows you to Rename Inputs.

Reset Input
Source

Select USB-C 90 W input when you are using the
USB-C 90 W connector. Press the joystick button to

confirm the selection.

connector. Press the joystick button to confirm the
selection.

connector. Press the joystick button to confirm the
selection.

scan for available input sources. Press the joystick button to
confirm the selection.

Allows you to set Auto Select for USB Type-C to:

• Prompt for Multiple Inputs: always show Switch to
USB Type-C Video Input message for user to choose
whether to switch or not.

• Yes: The monitor always switch to USB Type-C video
without asking while USB Type-C connected.

• No: The monitor will NOT auto switch to USB Type-C
video from another available input.

Resets all settings under the Input Source menu to the
factory defaults.

48 | Operating the monitor

Icon Menu and

Submenus

Color Use the Color menu to adjust the color setting mode.

Preset Modes When you select Preset Modes, you can choose Standard,

Description

Movie, Game, Color Temp. or Custom Color from the list.

• Standard: Default Color setting, This monitor uses a low

blue light panel, and is certied by TUV to reduce blue
light output and create a more relaxing and less stimulating
image while reading content on the screen.

• Movie: Ideal for movies.

• Game: Ideal for most gaming applications.

• Color Temp.: The screen appears warmer with a red/

yellow tint with slider set at 5,000K or cooler with blue tint
with slider set at 10,000K.

• Custom Color: Allows you to manually adjust the color
settings. Press the joystick left and right buttons to adjust
the Red, Green, and Blue values and create your own
preset color mode.

Operating the monitor | 49

Icon Menu and

Submenus

Input Color
Format

Hue Use joystick up or down to adjust the hue from 0 to 100.

Saturation Use joystick up or down to adjust the saturation from 0 to

Reset Color Resets your monitor’s color settings to the factory defaults.

Description

Allows you to set the video input mode to:

• RGB: Select this option if your monitor is connected to
a computer (or DVD player) using the USB Type-C, DP,
HDMI cable.

• YPbPr: Select this option if your DVD player supports only
YPbPr output.

NOTE: Hue adjustment is available only for Movie and
Game mode.

100.

NOTE: Saturation adjustment is available only for Movie
and Game mode.

50 | Operating the monitor

Icon Menu and

Submenus

Display Use the Display menu to adjust image.

Aspect Ratio Adjust the image ratio to Wide 16:10, 4:3, 5:4.

Sharpness Makes the image look sharper or softer.

Response
Time

MST DP Multi Stream Transport, Set to ON enables MST(DP

Reset Display Resets all settings under the Display menu to the factory

Description

Move the joystick up and down to adjust the sharpness
from ‘0’ to ‘100’.

Allows you to set the Response Time to Normal or Fast.

out), Set to OFF disables MST function.

NOTE: When DP/USB Type-C upstream cable and DP
downstream cable is connected, monitor will set MST =
ON automatically, this action will only be done once after
Factory Reset or Display Reset.

defaults.

Operating the monitor | 51

Icon Menu and

Submenus

Menu Select this option to adjust the settings of the OSD, such

Language Set the OSD display to one of eight languages.

Rotation Rotates the OSD by 0/90/180/270 degrees.

Transparency Select this option to change the menu transparency by

Timer OSD Hold Time: Sets the length of time the OSD remains

Description

as the languages of the OSD, the amount of time the menu
remains on screen, and so on.

(English, Spanish, French, German, Brazilian Portuguese,
Russian, Simplified Chinese, or Japanese).

You can adjust the menu according to your display rotation.

moving the joystick up or down (min. 0/max. 100).

active after you press a button.

Move the joystick to adjust the slider in 1-second
increments, from 5 to 60 seconds.

52 | Operating the monitor

Icon Menu and

Submenus

Lock With the control buttons on the monitor locked, you can

Reset Menu Resets all settings under the Reset menu to the factory

Description

prevent people from accessing the controls. It also prevents
accidental activation in multiple monitors side-by-side setup.

• Menu Buttons: Through OSD to lock the Menu buttons.

• Power Button: Through OSD to lock the Power button.

• Menu + Power Buttons: Through OSD to lock the all of
Menu and Power buttons.

• Disable: Move the Joystick left and hold for 4 sec.

defaults.

Operating the monitor | 53

Icon Menu and

Submenus

Personalize

Shortcut key 1

Shortcut key
2

Shortcut key
3

Shortcut key
4

Shortcut key
5

Power Button
LED

USB-C
Charging
90 W

Other USB
Charging

Reset
Persona­lization

Description

Select from Preset Modes, Brightness/Contrast, Input
Source, Aspect Ratio, Rotation, Display Info set as

shortcut key.

Allows you to set the state of the power light to save
energy.

Allows you to enable or disable USB-C Charging 90 W
charging function during monitor power off mode.

Allows you to enable or disable Other USB Charging
function during monitor Standby mode.

Resets all settings under the Personalize menu to the
factory preset values.

54 | Operating the monitor

Icon Menu and

Submenus

Others Select this option to adjust the OSD settings suchas the

Display Info Displays the monitor’s current settings.

DDC/CI DDC/CI (Display Data Channel/Command Interface) allows

Description

DDC/CI, LCD conditioning, and so on.

your monitor parameters (brightness, color balance, and
etc.) to be adjustable via the software on your computer.
You can disable this feature by selecting Off. Enable this
feature for best user experience and optimum performance
of your monitor.

Operating the monitor | 55

Icon Menu and

Submenus

LCD
Conditioning

Firmware Displays the firmware version of your monitor.
Service Tag Displays the Service Tag. The Service Tag is a unique

Reset Others Resets all settings under the Others menu to the factory

Factory Reset Restores all preset values to the factory default settings.

Description

Helps reduce minor cases of image retention. Depending on
the degree of image retention, the program may take some
time to run. You can enable this feature by selecting On.

alphanumeric identifier that allows Dell to identify the
product specifications and access warranty information.

NOTE: The Service Tag is also printed on a label located at
the back of the cover.

defaults.

56 | Operating the monitor

OSD warning messages

When the monitor does not support a particular resolution mode, you can see the
following message:

This means that the monitor cannot synchronize with the signal that it is receiving
from the computer. See Monitor Specifications for the Horizontal and Vertical
frequency ranges addressable by this monitor. Recommended mode is 1920 x 1200.

You can see the following message before the DDC/CI function is disabled:

When the monitor enters the Standby mode, the following message will appear:

Activate the computer and wake up the monitor to gain access to the OSD.

If you press any button other than the power button, the following messages will
appear depending on the selected input:

Operating the monitor | 57

A message is displayed while the cable supporting DP alternate mode is connected to
the monitor under the following conditions:

• When Auto Select for USB-C is set to Prompt for Multiple Inputs.

• When the USB-C cable is connected to the monitor.

Select OSD items of Factory Reset in Other feature, the following message will
appear:

When you select ‘Yes ‘ to reset to default settings, the following message will appear:

58 | Operating the monitor

Select OSD items of On in Standby Mode in Personalize feature, the following
message will appear:

If adjust the Brightness level above the default level over 75%, the following message
will appear:

• When user selects “Yes”, the power message is displayed only once.

• When user select ‘No’, the power warning message will pop-up again.

• The power warning message will appear again only when the user does a Factory
Reset from the OSD menu.

Operating the monitor | 59

If either USB Type-C, DP, HDMI input is selected and the corresponding cable is not
connected, a floating dialog box as shown below appears.

or

or

See Troubleshooting for more information.

60 | Operating the monitor

Setting the maximum resolution

To set the maximum resolution for the monitor:

In Windows 7, Windows 8 or Windows 8.1:

1. For Windows 8 or Windows 8.1 only, select the Desktop tile to switch to classic
desktop. For Windows Vista and Windows 7, skip this step.

2. Right-click on the desktop and click Screen Resolution.

3. Click the Dropdown list of the Screen Resolution and select 1920 x 1200.

4. Click OK.

In Windows 10:

1. Right-click on the desktop and click Display Settings.

2. Click Advanced display settings.

3. Click the dropdown list of Resolution and select 1920 x 1200.

4. Click Apply.

If you do not see 1920 x 1200 as an option, you may need to update your graphics
driver. Depending on your computer, complete one of the following procedures:

If you have a Dell desktop or portable computer:

• Go to http://www.dell.com/support, enter your service tag, and download the
latest driver for your graphics card.

If you are using a non-Dell computer (laptop or desktop):

• Go to your computer manufacturer’s support website and download the latest
graphic drivers.

• Go to your graphics card manufacturer’s website and download the latest graphic
drivers.

Operating the monitor | 61

Troubleshooting

WARNING: Before you begin any of the procedures in this section, follow

the Safety Instructions.

Self-test

Your monitor provides a self-test feature that allows you to check whether your
monitor is functioning properly. If your monitor and computer are properly connected
but the monitor screen remains dark, run the monitor self-test by performing the
following steps:

1. Turn o both your computer and the monitor.

2. Unplug the video cable from the back of the computer. To ensure proper Self-Test

operation, remove all digital and the analog cables from the back of computer.

3. Turn on the monitor.

The floating dialog box should appear on-screen (against a black background), if the
monitor cannot sense a video signal and is working correctly. While in self-test mode,
the power LED remains white. Also, depending upon the selected input, one of the
dialogs shown below will continuously scroll through the screen.

or

or

4. This box also appears during normal system operation if the video cable
becomesdisconnected or damaged.

62 | Troubleshooting

5. Turn o your monitor and reconnect the video cable; then turn on both your

computer and the monitor.

If your monitor screen remains blank after you use the previous procedure, check your
video controller and computer, because your monitor is functioning properly.

Built-in diagnostics

Your monitor has a built-in diagnostic tool that helps you determine if the screen
abnormality you are experiencing is an inherent problem with your monitor, or with your
computer and video card.

Display Info

To run the built-in diagnostics:

1. Ensure that the screen is clean (no dust particles on the surface of the screen).

2. Press and hold Up or Down or Left or Right direction for four seconds until a

menu appears on the screen.

3. Using the joystick control, highlight the Diagnostics option and press the
joystick button to start the diagnostics. A gray screen is displayed.

4. Observe if the screen has any defects or abnormalities.

5. Toggle the joystick once again until a red screen is displayed.

6. Observe if the screen has any defects or abnormalities.

7. Repeat steps 5 and 6 until the screen displays green, blue, black, and white

colors. Note any abnormalities or defects.

The test is complete when a text screen is displayed. To exit, toggle the joystick control
again.

If you do not detect any screen abnormalities upon using the built-in diagnostic tool,
the monitor is functioning properly. Check the video card and computer.

Troubleshooting | 63

Common Problems

The following table contains general information about common monitor problems you
might encounter and the possible solutions:

Common
Symptoms

No Video/
Power LED off

No Video/
Power LED on

Missing Pixels LCD screen has

Stuck-on Pixels LCD screen has

Brightness
Problems

Safety Related
Issues

What You
Experience

No picture • Ensure that the video cable connecting the

No picture or no
brightness

spots

bright spots

Picture too dim
or too bright

Visible signs of
smoke or sparks

Possible Solutions

monitor and the computer is properly connected
and secure.

• Verify that the power outlet is functioning
properly using any other electrical equipment.

• Ensure that the power button is depressed fully.

• Ensure that the correct input source is selected
in the Input Source menu.

• Increase brightness and contrast controls via
OSD.

• Perform monitor self-test feature check.

• Check for bent or broken pins in the video cable
connector.

• Run the built-in diagnostics.

• Ensure that the correct input source is selected
in the Input Source menu.

• Cycle power on-off.

• Pixel that is permanently off is a natural defect

that can occur in LCD technology.

• For more information on Dell Monitor Quality

and Pixel Policy, see Dell Support site at:
www.dell.com/pixelguidelines.

• Cycle power On-Off.

• Pixel that is permanently off is a natural defect

that can occur in LCD technology.

• For more information on Dell Monitor Quality

and PixelPolicy, see Dell Support site at:
www.dell.com/pixelguidelines.

• Reset the monitor to factory settings.

• Adjust brightness and contrast controls via OSD.

• Do not perform any troubleshooting steps.

• Contact Dell immediately.

64 | Troubleshooting

Common
Symptoms

Intermittent
Problems

Missing Color Picture missing

Wrong Color Picture color

Image retention
from a static
image left on
the monitor for
a long period of
time

What You
Experience

Monitor
malfunctions on
& off

color

not good

Faint shadow
from the static
image displayed
appears on the
screen

Possible Solutions

• Ensure that the video cable connecting the
monitor to the computer is connected properly
and is secure.

• Reset the monitor to factory settings.

• Perform monitor self-test feature check to
determine if the intermittent problem occurs in
self-test mode.

• Perform monitor self-test.

• Ensure that the video cable connecting the
monitor to the computer is connected properly
and is secure.

• Check for bent or broken pins in the video cable
connector.

• Change the settings of the Preset Modes in the
Color menu OSD depending on the application.

• Adjust R/G/B value under Custom Color in Color
menu OSD.

• Change the Input Color Format to PC RGB or
YPbPr in the Color menu OSD.

• Run the built-in diagnostics.

• Set the screen to turn o after a few minutes
of screen idle time. These can be adjusted in
Windows Power Options or Mac Energy Saver
setting.

• Alternatively, use a dynamically changing
screensaver.

Product specific problems

Problem What you

experience

Screen image is
too small

Image is
centered on
screen, but
does not fill
entire viewing
area

Possible solutions

• Check the Aspect Ratio setting in the Display
menu OSD.

• Reset the monitor to factory settings.

Troubleshooting | 65

Problem What you

experience

Cannot adjust
the monitor
with the
buttons on the
front panel

No Input Signal
when user
controls are
pressed

The picture
does not fill the
entire screen

No image
when using DP
connection to
the PC

No image
when using
USB Type-C
connection
to computer,
laptop, and so
on

OSD does not
appear on the
screen

No picture, the
LED light is
white

The picture
cannot fill the
height or width
of the screen

Black screen • Verify which DP standard (DP 1.1a or DP 1.4) is

Black screen • Verify if the USB Type-C interface of the device

Possible solutions

• Turn o the monitor, unplug the monitor power
cable, plug it back, and then turn on the monitor.

• Check the signal source. Ensure the computer
is not in the power saving mode by moving the
mouse or pressing any key on the keyboard.

• Check whether the signal cable is plugged
in properly. Connect the signal cable again, if
necessary.

• Reset the computer or video player.

• Due to dierent video formats (aspect ratio) of
DVDs, the monitor may display in full screen.

• Run the built-in diagnostics.

your Graphics Card certied to. Download and
install the latest graphics card driver.

• Some DP 1.1a graphics card cannot support
DP 1.4 monitors. Go to OSD menu, under Input
Source selection, press and hold DP select
joystick key for 8 sec to change the monitor
setting from DP 1.4 to DP 1.1a.

can support DP alternate mode.

• Verify if the device required more than 90 W
power charging.

• USB Type-C interface of device cannot support
DP alternate mode.

• Set Windows to Projection mode.

• Ensure that the USB Type-C cable is not
damaged.

66 | Troubleshooting

Problem What you

experience

No charging
when using
USB Type-C
connection
to computer,
laptop, and so
on

Intermittent
charging
when using
USB Type-C
connection to
computer,

laptop, and so
on

No image
when using DP
connection to
the PC

No image when
using USB
Type-C MST

No network
connection

No charging • Verify if the device can support one of 5 V/9

Intermittent
charging

Black screen • Verify which DP standard (DP 1.1a or DP 1.4) is

Black screen or

2nd DUT is not
Prime mode

Network
dropped or
Intermittent

Possible solutions

V/15 V/20 V charging proles.

• Verify if the Notebook requires a >90 W power
adaptor.

• If the Notebook requires a >90 W power
adaptor, it may not charge with the USB Type-C
connection.

• Ensure that you use only Dell approved adapter
or the adapter that comes with the product.

• Ensure that the USB Type-C cable is not
damaged.

• Check if the maximum power consumption of
device is over 90 W.

• Ensure that you use only Dell approved adapter
or the adapter that comes with the product.

• Ensure that the USB Type-C cable is not
damaged.

your Graphics Card certied to. Download and
install the latest graphics card driver.

• Some DP 1.1a graphics card cannot support

DP 1.4 monitors. Go to OSD menu, under Input
Source selection, press and hold DP select
key for 8 sec to change the monitor setting from
DP 1.4 to DP 1.1a.

• USB Type-C input, Go to OSD menu, under
Display Info check the Link Rate is HBR2 or
HBR3, if Link Rate is HBR2, suggest to use USB
Type-C to DP cable to turn on MST.

• Do not toggle O/On the power button when
network is connected, keeps the power button
On.

Troubleshooting | 67

Problem What you

experience

The LAN port is
not functioning

OS setting
or cable
connection
issue

Possible solutions

• Ensure that the latest BIOS and drivers for your
computer are installed on your computer.

• Ensure that the RealTek Gigabit Ethernet
Controller is installed in the Windows Device
Manager.

• If your BIOS Setup has a LAN/GBE Enabled/
Disabled option, make sure it is set to Enabled.

• Ensure that the Ethernet cable is connected
securely on the monitor and the hub/router/
rewall.

• Check the status LED of the Ethernet cable to
conrm connectivity. Re-connect both ends of
the Ethernet cable if the LED is not lit.

• First power o the Computer and unplug the
Type-C cable and power cord of the monitor.
Then, power on the computer, plug in the
monitor power cord and Type-C cable.

Universal Serial Bus (USB) specific problems

Specific
Symptoms

USB interface is
not working

68 | Troubleshooting

What You
Experience

USB peripherals
are not working

Possible Solutions

• Check that your display is turned ON.

• Reconnect the upstream cable to your
computer.

• Reconnect the USB peripherals (downstream
connector).

• Turn o the monitor and turn it on again.

• Reboot the computer.

• Certain USB devices such as portable hard
drives require higher power source; connect the
drive to the computer directly.

Specific
Symptoms

SuperSpeed
USB 3.2 Gen
1 interface is
slow.

Wireless USB
peripherals stop
working when a
USB 3.0 device
is plugged in

USB is not
working

What You
Experience

SuperSpeed
USB 3.2 Gen
1 peripherals
working slowly
or not working
at all

Wireless USB
peripherals
responding
slowly or only
working as
the distance
between itself
and its receiver
decreases

No USB
functionalities

Possible Solutions

• Check that your computer is USB 3.0-capable.

• Some computers have USB 3.0, USB 2.0, and
USB 1.1 ports. Ensure that the correct USB port
is used.

• Reconnect the upstream cable to your
computer.

• Reconnect the USB peripherals (downstream
connector).

• Reboot the computer.

• Increase the distance between the USB 3.0
peripherals and the wireless USB receiver.

• Position your wireless USB receiver as close as
possible to the wireless USB peripherals.

• Use a USB-extender cable to position the
wireless USB receiver as far away as possible
from the USB 3.0 port.

Refer to input source and USB pairing table.

Troubleshooting | 69

Appendix

FCC notices (U.S. only) and other regulatory information

For FCC notices and other regulatory information, see the regulatory compliance
website located at www.dell.com/regulatory_compliance.

Contacting Dell

For customers in the United States, call 800-WWW-DELL (800-999-3355).

EU product database for energy label and product information sheet

U2421E: https://eprel.ec.europa.eu/qr/344899

NOTE: If you do not have an active Internet connection, you can find

contact information on your purchase invoice, packing slip, bill, or Dell
product catalog.

Dell provides several online and telephone-based support and service options.
Availability varies by country and product, and some services may not be available in
your area.

To get online Monitor support content:

See www.dell.com/support/monitors.

To contact Dell for sales, technical support, or customer service issues:

1. Go to www.dell.com/support.

2. Verify your country or region in the Choose A Country/Region drop-down menu

at the bottom-right corner of the page.

3. Click Contact Us next to the country dropdown.

4. Select the appropriate service or support link based on your need.

5. Choose the method of contacting Dell that is convenient for you.

70 | Appendix