SanDisk Optimus GX PRO 850X

The Optimus GX PRO 850X is an endurance monster with 4800 TBW and top-tier random performance. If you write a lot of data and want a drive that won't die, this is your pick.

Sequential speeds land in the 87th percentile, which is strong but not the absolute fastest PCIe 4.0 drive we've tested. The random IOPS are where things get interesting. 1200K read and 1200K write put this in the 95th percentile, meaning it handles scattered small file operations like a champ. That's the stuff that actually makes Windows feel snappy and game loads feel instant. The DRAM-less design with SanDisk nCache 4.0 doesn't seem to hurt it much, though we'd love to see how it holds up under sustained heavy writes. The endurance rating is the real flex here, 4800 TBW on a 1TB drive is absurdly good.

The Samsung 990 PRO is the obvious rival here. It's faster on sequential reads and has a bigger brand footprint, but its endurance rating is roughly a third of what the Optimus GX PRO 850X offers. The WD Black SN850X is another strong competitor with similar speed but again, nowhere near the TBW rating. The Micron T710 is interesting if you want enterprise-grade reliability in a consumer form factor, but it's harder to find and usually pricier. For pure endurance per dollar, the SanDisk wins this round. For raw sequential speed, the 990 PRO still takes the crown.

Pricing is all over the place. In the US you'll see anywhere from USD 225 to USD 290 depending on the vendor, with Newegg listings at the lower end of that spread. In Europe it's EUR 277 to EUR 306, with the best EUR deals showing up in Germany and Spain. For a drive with this endurance rating and random performance, the lower end of those ranges is a solid deal. At the top end, you're paying Samsung 990 PRO money for slightly less sequential speed but way more endurance. If you can snag it near USD 225 or EUR 277, it's a no-brainer for a workstation drive.

The SanDisk Optimus GX PRO 850X is a PCIe 4.0 drive that punches way above its weight class in endurance and random performance. The headline numbers are 7300 MB/s read and 6600 MB/s write, but the real story is the 4800 TBW endurance rating. That's top of the charts for this category, and it means this drive is built to get hammered daily without flinching. If you're a creator who writes terabytes of footage every month, this is the drive that won't quietly die on you.

If you're building a portable rig or need something for a laptop, skip this. The portable score is one of the worst we've seen, and there are better low-power options out there. If you just want the fastest sequential speeds for bragging rights, go grab a Samsung 990 PRO instead. This drive is for people who write a lot of data and want it to last forever.

The SanDisk Optimus GX PRO 850X is the endurance king of consumer PCIe 4.0 drives. If you're a video editor, 3D artist, or anyone who writes huge files constantly, this is the drive to buy. The random performance is excellent, the warranty is generous, and the price at the low end is very fair. It's not the fastest sequential drive on the market, but it's fast enough that you won't notice the difference in real-world use. Buy it for the longevity, stay for the snappy random performance.