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NAS Reviews

QNAP TS-251 & 451

At a Glance
Product QNAP TS-251 & TS-451 Turbo NASes [Website]
Summary Intel dual-core Celeron-powered NASes with dual Gigabit LAN, USB 3.0 and HDMI port.
Pros • Supports up to 8 GB of RAM
• Wide range of downloadable apps
• Quiet
• Updated user interface
Cons • TS-451 is expensive compared to similarly performing TS-469L


QNAP recently upgraded its Home and SOHO NAS family with the TS-x51 series with two, four, six and eight bay models. All share a common hardware platform with two variations. The white TS-251 (2 bay) and TS-451 (4 bay) use the same main board with two each USB 2.0 and USB 3.0 ports.

The black TS-651 (6 bay) and TS-851 (8 bay) share a different main board that supports three USB 3.0 ports. The larger models also use a different SATA device to support the greater number of drive bays. So while the family includes four models, this review will focus on the two and four-bay models.

QNAP TS-x51 product comparison

QNAP TS-x51 product comparison

Each product in the TS-X51 family is available with 1 GB or 4 GB (2 X 2 GB) of SoDIMM RAM that can be expanded to a total of 8 GB. The 4 GB model costs $60 more than the corresponding 1 GB model on Amazon. The additional power of the Celeron processor and additional memory will come in handy to support Virtualization Station and new QvPC features coming in QTS 4.1.2.

Below is a screenshot showing the callouts for the front and rear panels for the four models. Each front panel has LED indicators for each disk, power button, IR receiver, One Touch Copy button and a single USB 3.0 port. Although the TS-651 and 851 look like they have a status panel, the callouts show that all that's behind the dark plastic panel running along upper front panel is an IR receiver.

Front and rear panel callouts

Front and rear panel callouts

The TS-251 and 421 rear panels have a power connector for the external brick, two Gigabit LAN ports, reset button, two USB 2.0 ports, security slot, HDMI port and fan. The TS-651 and 851 have a built-in power supply so you'll find an AC receptacle. The TS-651 and 851 also have dual fans as well as two USB 3.0 ports (in addition to the one on the front panel).


We disassembled the TS-451 to take the photos and identify components. Disassembly is easy and QNAP even provides instructions. The easy backplane removal will be particularly welcome if you opt for a RAM upgrade.

All -x51 series models use a 2.41 GHz Intel Celeron J1800 (Bay Trail D) dual-core processor, sitting under the heatsink in the photo below. As noted earlier, the TS-651 and 851 use a different board with dual-stacked USB 3.0 and Gigabit Ethernet ports.

QNAP TS-451 main PCB

QNAP TS-451 main PCB

SATA for the 251 and 451 drive bays is provided by Asmedia ASM1061 dual-port PCIe to SATA host controllers mounted on the drive bay backplane. According to Legion Hardware's review, the 651 an 851 use Marvell 88SE9215 quad-port 6 Gb/s PCIe - SATA host controllers mounted on their larger drive backplanes.

QNAP TS-451 backplane PCB

QNAP TS-451 backplane PCB

Table 1 summarizes key components.

TS-251 / TS-451 TS-651 / TS-851
CPU Intel Celeron J1800 dual-core processor @ 2.41 GHz (Bay Trail D) Intel Celeron J1800 dual-core processor @ 2.41 GHz (Bay Trail D)
RAM 1 GB DDR3 SoDIMM (expandable to 8 GB) 1 GB DDR3 SoDIMM (expandable to 8 GB)
Flash 512 MB DOM 512 MB DOM
Ethernet Intel WGI210TA (x2) Intel WGI210TA (x2)
USB 3.0 Asmedia 1074 USB 3.0 quad port hub
Asmedia 1074 USB 3.0 quad port hub
SATA Asmedia ASM1061 (x2 for TS-451) Marvell 88SE9215 quad-port 6 Gb/s PCIe - SATA host controllers (x2)
HDMI Asmedia ASM1442 level shifter Asmedia ASM1442 level shifter
Table 1: Key component summary and comparison

QNAP equipped the TS-451 review sample with four Seagate NAS HDD 3 TB (ST3000VN000) drives for testing. Power consumption measured 31 W with the 4 drives spun up and 13 W with them spun down. With only two drives inserted for the TS-251 tests, power consumption dropped to 19W with the drives spun up. Fan and drive noise could be classified as low, i.e. barely audible in a quiet home office.

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