4TB M.2 NVMe Gen 4 SSDs

The 4TB PCIe Gen 4 M.2 drives here are all from WD's Black range: the WD Black SN7100 4TB (WDS400T4X0E), rated up to 7000 MB/s read and 6700 MB/s write, the WD Black SN850X 4TB (WDS400T2X0E), rated up to 7300/6600 MB/s, and the WD Black SN850X 4TB with Heatsink (WDS400T2XHE), the same drive with a factory-fitted heatsink. All three are M.2 2280 NVMe SSDs, and WD covers them with a 5 year warranty.

Choosing comes down to the machine. For a laptop or a mini PC, the bare SN7100 or bare SN850X fits; the SN7100 is a DRAM-less design that runs cool and draws little power, which suits thin laptops. The SN850X carries a DRAM cache and holds up better under long, heavy writes such as large game installs, video projects or big file copies. On a desktop board that already has an M.2 cover, use the bare SN850X; if the slot is uncovered, or the drive is going into a PlayStation 5, the heatsink version handles cooling on its own. The heatsink model is too tall for most laptops.

Frequently asked questions

Will a Gen 4 SSD work in a Gen 3 or Gen 5 M.2 slot? Yes. In a Gen 3 slot it runs at Gen 3 speeds, and in a Gen 5 slot it runs at its full Gen 4 speed.

What is the difference between the SN7100 and the SN850X? The SN850X is slightly faster on reads and has a DRAM cache for sustained workloads, while the SN7100 is DRAM-less and more power-efficient.

Which 4TB drive suits a PS5? The WD Black SN850X with Heatsink, since the PS5 expansion slot needs a Gen 4 drive with cooling fitted.