Side-by-side: WD_BLACK SN850X 4TB ($535) vs WD_BLACK SN7100 4TB ($570). $/TB winner, specs, real-world picks for July 2026.
Gen 4 at 4 TB is one of the most contested SSD segments in 2026, and WD_BLACK SN850X 4TB versus WD_BLACK SN7100 4TB captures that competition well. The decision rarely comes down to peak speeds — both drives saturate typical workloads.
Hardware-wise, the WD_BLACK SN850X 4TB runs on WD's second-generation G2 in-house controller, tuned for sustained gaming I/O. The WD_BLACK SN7100 4TB pairs SanDisk's A101 controller, used in newer WD_BLACK SKUs after the SanDisk spinoff.
The DRAM-vs-HMB question divides opinion: WD_BLACK SN850X 4TB's on-board DRAM theoretically helps under sustained workloads, while WD_BLACK SN7100 4TB's HMB approach has matured enough that most users won't see the difference. Pick on price if everything else is similar.
If this purchase is for a PS5 storage expansion, the comparison flattens — Sony's PCIe Gen 4 controller normalizes both WD_BLACK SN850X 4TB and WD_BLACK SN7100 4TB to roughly equal in-game load times. The cheaper drive is the smart pick. Both drives use the 2280 form factor, which is too long for Steam Deck or ROG Ally — you'd need a 2230 variant if either manufacturer offers one, or a dedicated handheld-format drive instead.
How do these two fit the wider Gen 4 4 TB field? Out of 6 tracked drives, the WD_BLACK SN850X 4TB is #4 on $/TB and the WD_BLACK SN7100 4TB is #5. Neither cracks the top of the value table, so it's worth glancing at the alternatives below before picking either.
As of July 27, 2026, these tracked drives undercut both the WD_BLACK SN850X 4TB and WD_BLACK SN7100 4TB on $/TB:
Go with the WD_BLACK SN850X 4TB for the lower retail price ($535 vs $570), better $/TB economics ($133.75/TB), and a dedicated DRAM cache chip. The SN850X has been the best-selling Gen 4 NVMe in PCPartPicker builds for two consecutive years — Game Mode 2.0 prioritizes I/O when supported titles need it.
The WD_BLACK SN7100 4TB fits buyers who prefer its specific performance profile or have brand preference for WD.