Western Digital Black SN850X 4Tb NVMe detailed specs

Posted on December 15, 2022 by Raymond Chen

Western Digital's Black SN850X SSD use PCIe M.2 4.0 x 4 expansion standard. Detailed characteristics of this NVMe SSD in our article.

Western Digital Black SN850X 4Tb NVMe detailed specs

Western Digital's 4Tb Black SN850X NVMe is powered by SanDisk 20-82-20035. The SSD storing a data location map on Dynamic-Random Access Memory LPDDR4 to launch a programs faster. The Black SN850X comes equipped with 112L Bics5 flash memory. Western Digital Black SN850X also available in 2 Tb and 1 Tb capacities.

Performance and benchmarks

SSD use PCIe M.2 4.0 x 4 with maximum write speeds 6600 MB/s, and read speeds 7300 MB/s. This model has IOPS 1200000 on writing and 1200000 on reading operations.

Endurance and warranty

Western Digital provide 5 years warranty for this product that limited by 2400 TBW.


Category Value
Capacity 4 Tb
Interface M.2 4.0 x 4
Controller SanDisk 20-82-20035
Memory type 112L Bics5
Read speed (Mb/s) 7300
Write speed (Mb/s) 6600
Read IOPS 1200000
Write IOPS 1200000
Endurance (TBW) 2400
MTBF (million hours) n/a
Warranty (years) 5


Black SN850X (4Tb) produced by Western Digital use PCIe 4 that is significantly faster than previous bus standard. The maximum write speed is 6600 Mbps, that is faster than has most of rivals. The NVMe provide possibility to write 2400 TBW, that is bad compared to competitors. After evaluating all the facts, we strongly advise to purchase Western Digital Black SN850X 4Tb for your PC.

+ Pros

  • Excellent writing speed
  • PCIe 4.0
  • Capacity

- Cons

  • Writing speed

Buy this or similar SSD:

Video Review

WD Black SN850X SSD Review


The Western Digital Black SN850X has LPDDR4. Dynamic Random-Access Memory in their controller help to increase input/output performance and endurance.

The Western Digital Black SN850X due to the high density of memory chips require the installation of additional heat sink. This decrease temperature of the memory chips and controller. Some motherboards or laptops already has additional cooling below or above the drive to improve performance during high loads.

The Western Digital Black SN850X has write speed 6600 Mbps, sequential read speed 7300 Mb per second. Storage operate on SanDisk 20-82-20035 controller and M.2 4.0 x 4 high-speed serial computer expansion bus standard. The NAND flash memory type is 112L Bics5.
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