Verdict

For a NAS cache or write-heavy pool, the WDS400T4X0E is the safer pick - the WDS400T4B0E uses QLC NAND, which wears out faster and slows badly under sustained writes (light, read-mostly use only).

WDS400T4B0E
WD Blue SN5000 · 4TB · Desktop
$490 ($122.50/TB)
WDS400T4X0E
WD Black SN7100 · 4TB · Desktop
$575 ($143.75/TB)

Value at a glance

Price / TB
WDS400T4B0E $121.36
WDS400T4X0E $134.97
Endurance (TBW)
WDS400T4B0E 1,200 TB
WDS400T4X0E 2,400 TB

Price history

US · cheapest per day

WDS400T4B0E $490 WDS400T4X0E $575
zoomed · drag to zoom
$580 $511 $443 Aug 21 Aug 26 Aug 31 Sep 5 Sep 10 Sep 16
WDS400T4B0E WDS400T4X0E
Capacity 4 TB 4 TB
Form factor M.2 M.2
Interface NVMe NVMe
NAND type QLC TLC
Endurance (TBW) 1,200 TB 2,400 TB
DWPD - -
DRAM cache No No
Power-loss protection No No
Sustained write - -
Cost / TBW $0.405 $0.225
Price / TB $121.36 $134.97
Buy
$490
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$575
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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.

WDS400T4B0E

No Backblaze failure data for this model.

WDS400T4X0E

No Backblaze failure data for this model.