Verdict

For a NAS cache or write-heavy pool, the WDS400T2X0E is the safer pick - the WDS400T4B0E uses QLC NAND, which wears out faster and slows badly under sustained writes (light, read-mostly use only).

WDS400T2X0E
WD Black SN850X · 4TB · Desktop
No CA price yet
WDS400T4B0E
WD Blue SN5000 · 4TB · Desktop
C$665 (C$166.25/TB)

Value at a glance

Price / TB
WDS400T2X0E $170.00
WDS400T4B0E $121.36
Endurance (TBW)
WDS400T2X0E 2,400 TB
WDS400T4B0E 1,200 TB

Price history

CA · cheapest per day

WDS400T4B0E C$665
zoomed · drag to zoom
C$693 C$647 C$600 Aug 21 Aug 26 Aug 31 Sep 5 Sep 10 Sep 16
WDS400T2X0E WDS400T4B0E
Capacity 4 TB 4 TB
Form factor M.2 M.2
Interface NVMe NVMe
NAND type TLC QLC
Endurance (TBW) 2,400 TB 1,200 TB
DWPD - -
DRAM cache Yes No
Power-loss protection No No
Sustained write - -
Cost / TBW $0.283 $0.405
Price / TB $170.00 $121.36
Buy No CA price yet
C$665
View at Amazon →

Highlighted cells mark the stronger spec for a NAS build. Failure rates from Backblaze Drive Stats where available; $/TB uses the cheapest live price. Buy links are Amazon affiliate.

WDS400T2X0E

No Backblaze failure data for this model.

WDS400T4B0E

No Backblaze failure data for this model.