QNAP TS-251B-4G User Manual

Hardware Specification

TS-251B-4G

CPU Intel® Celeron® J3355 dual-core 2.0 GHz processor (burst up to 2.5 GHz)

Architecture: 64-bit x86

Graphics Intel® HD Graphics 500

Encryption Acceleration Yes (AES-NI)

System Memory 4 GB DDR3L (1 x 4 GB)

Maximum Memory 8 GB (2 x 4 GB)

Memory Slot 2 x SODIMM DDR3L up to 1866, with dual-channel support

Flash Memory 4GB eMMC

Drive Bay 2 x 3.5" SATA 6 Gbps HDD

Drive Compatibility 3.5" SATA 6Gb/s HDD

2.5" SATA 6Gb/s HDD

2.5" SATA 6Gb/s SSD

SSD Cache Acceleration Support 3.5" drive bay：1 to 2

Gigabit Ethernet Port 1 x RJ45

USB Port 2 x USB 3.0, 3 x USB 2.0

USB One Touch Copy Front：USB 3.0 Type-A

PCIe Slot 1 PCIe 2.0 x2 slot

HDMI Output 1 x HDMI v1.4b (up to 3840 x 2160 resolution at 30 Hz)

IR sensor Yes , supporting QNAP RM-IR004 remote control (optional purchase)

Audio 1 x speaker, 2 x MIC Input

1 x 3.5 mm line-out jack
Alarm buzzer
Note: You cannot use the speakers and the line-out jack simultaneously.

LED Indicators Status/power、LAN、USB、HDD 1 - 2

Buttons Power, Reset, USB One-touch-copy

System Warning Alarm buzzer and voice prompts

Form Factor Tower

Dimensions (H x W x D) 168 x 105 x 226 mm ( 6.61 x 4.13 x 8.90 inch)

Net Weight 1.53 kg (3.37 lbs)

Power Consumption (W) HDD standby：8.08 W

In operation：15.25 W
(with 2 x 1TB HDDs installed)

Sound Level Sound pressure (LpAm): 17.3 dB(A)

Power Supply Unit 65W AC adapter, 100-240V

Fan 1 x 7 cm

Operating Temperature & Relative
Humidity

0 ~ 40˚C ( 32˚F ~ 104˚F ), 5 ~ 95% RH non-condensing, wet bulb: 27˚C
(80.6˚F)

Other Interfaces Kensington security slot

Note: Use only QNAP memory modules to maintain system performance and stability. For NAS devices with more than one memory
slot, use QNAP modules with identical specifications. Warning: Using unsupported modules may degrade performance, cause
errors, or prevent the operating system from starting.
* Sound Level Test Environment: Refer to ISO 7779; Maximum HDD loaded; Bystander Position; Average data from 1 meter in front
of operating NAS.
Designs and specifications are subject to change without notice.