WD Black SN850X - M.2 PCIe Gen4 NVMe SSD - 4TB

The WD Black SN850X is WD's flagship Gen4 NVMe drive, positioned squarely at gamers and power users who want the best performance current mainstream platforms can deliver. It succeeded the SN850 with modest spec improvements and added a heatsink variant, the latter matters more than the speed bump on paper.

Performance

Sequential reads top out at 7300 MB/s and writes at 6600 MB/s, putting it at the top of the Gen4 field. WD's proprietary controller pairs with a DRAM cache, which keeps random I/O consistent under sustained load, something DRAMless drives struggle with. The SN850X also carries PS5 compatibility certification, making it one of the cleaner console upgrade options without thermal workarounds.

Capacities and Endurance

Available in 1TB, 2TB, and 4TB. The 4TB variant carries a 2400 TBW endurance rating, which is generous for a consumer drive. All capacities include a 5-year warranty.

Thermals

The heatsink variant adds meaningful thermal headroom if your motherboard slot is open and positioned near hot components. Without the heatsink, sustained workloads in cramped cases can trigger throttling. If your board has a built-in M.2 heatsink, skip the heatsink SKU.

Limitations

This is a Gen4 drive in a world where Gen5 hardware is shipping. For desktops on a recent Intel or AMD platform, Gen5 options now exist at competitive prices. The SN850X's value proposition depends on whether your platform tops out at Gen4. For AM4, older Intel, and PS5, it remains one of the best choices.

Best for: Gamers on AM4 or older Intel platforms, PS5 upgrades, and anyone who wants a well-validated Gen4 drive with strong endurance and a heatsink option.

Avoid if: You're building on AM5 or Intel 12th gen+ and willing to spend more for Gen5 sequential speeds, or if your use case is primarily sequential throughput where Gen5 drives offer a clear generational step up.