Interface
WD BLACK SN850X 4TB with heatsinkPCIe 4.0 ×4 / NVMe
Samsung 990 PRO 4TBPCIe 4.0 ×4 / NVMe 2.0
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What changes?
The differences at a glance
Manufacturer facts for these exact variants. The order does not declare a performance winner.
DRAM cache
WD BLACK SN850X 4TB with heatsinkUnknown
Samsung 990 PRO 4TB4 GB
Cache arrangement
WD BLACK SN850X 4TB with heatsinkUnknown
Samsung 990 PRO 4TB4 GB DRAM
BLACK SN850X 4TB with heatsink: 3 unknown fields · 990 PRO 4TB: 3 unknown fields. Unknown does not mean absent.
Compare capacity and cache, not just peak speed
Manufacturer speeds are maxima under stated test conditions. They do not show sustained writing after the cache fills. TBW is a write-endurance warranty limit, not a predicted failure date; time limits also apply. Check M.2 length, interface and heatsink clearance in the host manual. Price per TB uses nominal decimal capacity and a confirmed delivered total.
| Specifications | WDBLACK SN850X 4TB with heatsinkWDS400T2XHERemove | Samsung990 PRO 4TBMZ-V9P4T0BWRemove |
|---|---|---|
| Interface | PCIe 4.0 ×4 / NVMe | PCIe 4.0 ×4 / NVMe 2.0 |
| Sequential read, up to | 7300 MB/s | 7450 MB/s |
| Sequential write, up to | 6600 MB/s | 6900 MB/s |
| NAND type | TLC 3D NAND | TLC V-NAND |
| DRAM cache | Unknown | 4 GB |
| Controller | Unknown | Samsung in-house |
| Random read, up to | 1200000 IOPS | Unknown |
| Factory heatsink | Yes | Unknown |
| Drive height, up to | 10.31 mm | Unknown |
| Cache arrangement | Unknown | 4 GB DRAM |
| Shop offers | €999.00€249.75 / TB · confirmed delivered total | No verified offers yet |
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