QNAP TS-251D

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Status: Legacy / discontinued

A 2-bay desktop NAS from 2020 with a dual-core Intel Celeron and an HDMI 2.0 port for 4K playback straight to a TV. It ships with 2 or 4 GB of RAM (up to 8 GB) and has hot-swap bays. A PCIe slot lets you add 2.5GbE, 5GbE or 10GbE networking or M.2 caching later.

Bays	2
CPU	Intel Celeron J4025; Intel Celeron J4005
Cores / Threads	2 / 2
RAM	2 GB or 4 GB installed (varies by SKU)
Product category	-
Badge	-
Hardware support status	Discontinued
OS/app support	Full
Technical support end	Active
Recommended replacement	TS-262
Release year	2020
RAID levels	Single, JBOD, RAID 0, RAID 1
PCIe slot types	1x PCIe Gen 2 x4
RAM (max)	8 GB
Memory slots	2
Memory generation	DDR4
Memory speed (MT/s)	2400 MT/s
ECC memory	Non-ECC
Memory module type	SODIMM
Replaceable memory	Replaceable
Network ports	1x Gigabit Ethernet Port (RJ45)
USB ports	2x USB 3.2 Gen 1 + 3x USB 2.0
PCIe expansion	1
M.2 slots	2
Drive bay types	3.5-inch SATA hard disk drives; 2.5-inch SATA solid state drives
Hot-swappable bays	Yes
CPU frequency (GHz)	2.7
Power draw, active (W)	15.25
Power draw, hibernation (W)	8.08
Power supply (W)	65
Dimensions H x W x D	6.6 x 4.1 x 8.9 in (168 x 105 x 226 mm)
Weight	3.3 lb (1.48 kg)
Largest certified configuration observed	36 TB (2 x Toshiba HDWG51JUZSVA, largest drive on the vendor HCL today; not a hardware limit)
Estimated cost to fill every bay with a certified 8 TB drive	about $633 new (Seagate ST8000VN004) / about $630 refurbished (Seagate ST8000NE001) / about $410 used (Western Digital WD80EFZX) -- one observed eBay unit price incl. shipping x bays; quantity availability unverified
Estimated cost to fill every bay with a certified 16 TB drive	about $1,000 new (Seagate ST16000NM000J) / about $850 refurbished (Seagate ST16000NM001G) / about $618 used (Seagate ST16000NM001G) -- one observed eBay unit price incl. shipping x bays; quantity availability unverified

View on Amazon Search eBay (used from $375.74) + Compare

2 eBay listings checked Nov 9, 2026 · 0 new, 2 used

Documents

• Product User Guide (PDF)

Compatible Drives

258 drives certified on TS-251D's official manufacturer compatibility list, sourced directly from QNAP's own published Hardware Compatibility List. Each model links to that drive's own compatibility page.

Certified list last checked 2026-09-16.

Compatible Memory

2 memory modules listed by QNAP as compatible with TS-251D. Third-party modules may also work, but are not shown here unless QNAP itself lists them as compatible.

Certified list last checked 2026-09-09. Coverage varies by model. Rated module speed is not a guarantee of NAS operating speed; follow the NAS maximum capacity and installation rules.

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