Western Digital BLACK SN850X 4TB SSD

Western Digital BLACK SN850X 4TB NVMe Gen4 PCIe M.2 2280 WDS400T2X0E

Western Digital BLACK SN850X 4TB NVMe Gen4 PCIe M.2 2280 WDS400T2X0E

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  • Get the ultimate gaming edge over your competition with insane speeds up to 7,300 MB/s(1) for top-level performance and ridiculously short load times. | (1) Based on read speed, unless otherwise stated. 1 MB/s = 1 million bytes per second. Based on internal testing; performance may vary depending upon host device, usage conditions, drive capacity, and other factors.
  • Soup up your gaming experience with extremely low latency that loads graphics fast with minimal stutter and lagging for smooth, satisfying action.
  • A range of capacities available in 1TB to 4TB(2) means you get to keep more of today’s games that can take up 200GB(2) or more of storage. | (2) 1GB = 1 billion bytes and 1TB = 1 trillion bytes. Actual user capacity may be less depending on operating environment.
  • The 1TB and 2TB(2) drives have an optional version with RGB lighting plus heatsink to help maintain peak performance through the most intense gaming sessions.
  • Game Mode 2.0 serves up even more PC performance-boosting features like load prediction to ready game assets for fast in-game loading.

Specifications Overview

Model WDS400T2X0E
Release Date August 2022

* First availability for purchase, it may not correspond to the actual market launch date.

Series BLACK SN850X NVMe
Capacity 4000 GB
Interface PCIe Gen4 x4
Form Factor M.2-2280
SSD Controller 20-82-20035-B1
NAND Flash Type BiCS5 112-layer TLC
Max Sequential Read Up to 7300 MB/s
Max Sequential Write Up to 6600 MB/s
MTBF 1.75M Hours

Western Digital BLACK SN850X 4TB Performance comparison with similar Solid State Drives

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Expert reviews


The WD Black SN850X is a powerful, high-end PCIe 4.0 SSD that's near the top of the heap in almost every category. The SN850X is available in high capacities and has an optional RGB-laden heatsink for most models, but pricing and the questionable Game Mode 2.0 keep it from being the very best.

Tom's Hardware

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The WD Black SN850X takes the company's flagship PCIe 4.0 gaming SSD and makes it even better, offering higher capacity and improved test results (including a new PC Labs record in the 3DMark Storage benchmark). About all it lacks is hardware-based security.


WD's Black SN850 drive was already a very good flagship drive but with an upgrade from 96-layer to 112-layer NAND and improvements to the firmware, the SN850X takes over that mantle with great effect. But the price could do with some tweaking.

Compare Western Digital BLACK SN850X 4TB with similar Solid State Drives

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