The Western Digital SN850X is a solid-state drive in the M.2 2280 form factor, launched on May 9th, 2022. It is available in capacities ranging from 1 TB to 4 TB. This page reports specifications for the 1 TB variant. With the rest of the system, the Western Digital SN850X interfaces using a PCI-Express 4.0 x4 connection. The SSD controller is the Black G2 (20-82-20035-B2) from WD, a DRAM cache chip is available. Western Digital has installed 112-layer TLC NAND flash on the SN850X, the flash chips are made by Kioxia. To improve write speeds, a pseudo-SLC cache is used, so bursts of incoming writes are absorbed more quickly. The cache is sized at 300 GB, once it is full, writes complete at 1500 MB/s. Copying data out of the SLC cache (folding) completes at 900 MB/s. Thanks to support for the fast PCI-Express 4.0 interface, performance is excellent. The SN850X is rated for sequential read speeds of up to 7,300 MB/s and 6,300 MB/s write; random IO reaches 800K IOPS for read and 1100K for writes.
At its launch, the SSD was priced at 189 USD. The warranty length is set to five years, which is an excellent warranty period. Western Digital guarantees an endurance rating of 600 TBW, a typical value for consumer SSDs.