SanDisk Optimus GX PRO 850X

The SanDisk Optimus GX PRO 850X is a 4TB Gen4 SSD with a ridiculous 4,800 TBW endurance rating and random performance in the 96th percentile. Sequential speeds are strong but not the fastest, and US pricing swings from $850 to $1,578. At the low end, it's a killer deal for creators who write tons of data.

Sequential reads land at 7,300 MB/s and writes at 6,600 MB/s, which puts this drive in the 88th percentile for speed. That's not quite Samsung 9100 PRO territory, but it's fast enough to make game load times and 4K video scrubbing feel instant. Random performance is where this thing shines, sitting in the 96th percentile, so heavy multitasking and DirectStorage titles should feel buttery. The TLC NAND paired with nCache 4.0 keeps sustained writes from falling off a cliff, though we'd like to see how it handles a completely full drive.

Against the Samsung 9100 PRO, the Optimus GX PRO 850X gives up some sequential speed but fights back with better endurance and a lower entry price. The WD_BLACK SN850X is a closer match on speed and often cheaper, but its endurance rating doesn't touch this SanDisk. The Crucial T710 and Kingston Fury Renegade are both solid Gen4 options, but neither offers the same combination of 4TB capacity, 4,800 TBW endurance, and hardware encryption. The Seagate FireCuda 530R is the closest on endurance, but it's usually priced higher per gigabyte.

Pricing is all over the place right now. US listings range from $850 to $1,578, which is a $728 spread for the exact same drive. That's not a typo. If you're shopping in the US, do yourself a favor and hunt down the $850 listing before even thinking about the higher ones. At the low end, you're getting a 4TB drive with top-tier endurance and near-top-tier speed for a reasonable price. At the high end, you're paying Samsung 9100 PRO money for a drive that doesn't quite match it on sequential reads.

The SanDisk Optimus GX PRO 850X is a 4TB PCIe 4.0 drive aimed squarely at gamers and creators who are tired of juggling storage. It hits 7,300 MB/s reads and 6,600 MB/s writes, which puts it near the top of the Gen4 food chain. The endurance rating is the real headline here, 4,800 TBW on this 4TB model, which is frankly overkill for most people and we love it.

SanDisk packed in TCG Opal hardware encryption and their nCache 4.0 tech to keep things snappy under load. It's not the absolute fastest Gen4 drive in our database, but it's close enough that you'd never notice without a benchmark open. The 5-year warranty backs up the endurance story nicely.

Skip this if you're just looking for a boot drive or a place to park some games. The endurance rating is wasted on light workloads, and you can get a 4TB Gen4 drive for less money if you don't need the TBW headroom. Also skip it if you're paying anywhere near the $1,578 end of the price range, that's Samsung 9100 PRO money for a drive that isn't quite as fast.

This drive is for people who write a lot of data and don't want to think about their SSD dying. Video editors, 3D artists, and anyone who churns through terabytes of renders will appreciate the 4,800 TBW rating. Gamers who just want a big, fast drive will also be happy, though they might find better value elsewhere if they don't need the endurance. If you can snag it at the low end of that price range, it's an easy recommendation.