Lusting After an 8TB SSD? Don’t Wait: This 4.5-Star WD M.2 Model Just Hit $530 for Prime Day

When I reviewed the WD Black SN850X and gave it a near-perfect 4.5-star rating and our Editors’ Choice award, this wicked-fast internal SSD was only available in capacities up to 4TB. An 8TB version is now available, and for Prime Day, it’s on sale for 40% off its list price. (It was discounted slightly less earlier in the week; it just hit 40% this morning, as Prime Day is winding down.) At its deal price of $530, its cost per gigabyte comes to 6.6 cents, a great rate for an elite SSD of such massive capacity. Usually, you pay a hefty premium in terms of cost per gigabyte (not just in the total cost) for SSDs at the rarefied 8TB capacity. Not so with this one, in this sale.

Whether you’re a gamer, a content creator, or a power user looking to upgrade your rig, adding this stick can give your system a substantial boost in both performance and capacity. The SN850X is a four-lane solid-state drive running the NVMe 1.4 protocol over a PCI Express 4.0 bus. It is manufactured on an M.2 Type-2280 (80mm long) “gumstick” printed circuit board, and should work with any late-model desktop motherboard with a PCIe 4.0 M.2 slot. It employs 112-layer TLC 3D NAND flash memory and a homegrown WD/SanDisk controller.

The SN850X awed us in our benchmark testing, posting top-tier sequential read and write results in Crystal DiskMark throughput testing, as well as a new high score in Crystal DiskMark’s 4K Write test. It turned in the second-highest score at the time in PCMark 10’s Overall Storage test, which measures a drive’s speed in performing a variety of routine tasks such as loading games and launching the Windows operating system and other programs. It even set a high score in 3DMark Storage, a benchmark that aggregates the results of a series of gaming-related tasks. Although I reviewed the SN850X in late 2022, that high score still stands among the PCI Express 4.0 SSDs we have tested.

(Credit: Molly Flores)

Although a new generation of internal SSDs that employ the PCI Express 5.0 bus has landed, nearly doubling the throughput speeds of PCIe 4.0 sticks, they require cutting-edge hardware for optimal performance, with only some high-end desktops and very few laptops currently including M.2 slots that support the 5.0 standard. PCI Express 4.0 SSDs are more universally compatible, though many older systems still only support PCI Express 3.0, and it’s best to check which PCI Express flavor your setup supports before pulling the trigger. (A PCI Express 4.0 SSD will run in a PCI Express 3.0 M.2 slot, but at PCIe 3.0 speeds.)

Get Exclusive Savings!

Amazon Prime Day Returns July 8- 11

Sign up now for the Tech Deals newsletter to unlock our top editor-curated deals for Amazon’s huge shopping event.

Sign up now for the Tech Deals newsletter to unlock our top editor-curated deals for Amazon’s huge shopping event.

By clicking Sign Me Up, you confirm you are 16+ and agree to our Terms of Use and Privacy Policy.

Thanks for signing up!

Your subscription has been confirmed. Keep an eye on your inbox!

Also, raw throughput speed, as measured by Crystal DiskMark’s sequential read and write testing, does not always equate to superb everyday storage or gaming performance, which I measure via the PCMark 10 and 3DMark Storage benchmarks. In my review analysis of PCI Express 5.0 SSDs, I include the SN850X and one other of the top-scoring PCIe 4.0 SSDs, as well as a number of PCIe 5.0 SSDs, and the Gen 4 sticks usually give at least the lower-end Gen 5 SSDs a run for their money. So this on-sale drive is no slouch on speed.

The Prime Day deal for the WD Black SN850X gives you a chance to acquire one of our favorite elite PCI Express 4 SSDs at a monstrous capacity for a very competitive cost per gigabyte. It’s great for gamers who want a high-performance Gen 4 stick that can also hold a substantial game library, or content creators needing to quickly process myriad photos or high-res video. And it could be yours for a very reasonable price.

Also, be sure to check out more top Prime Day SSD deals in our comprehensive guide.

Best Tips for Prime Day 2025

About Tony Hoffman

Senior Analyst, Hardware

Since 2004, I have worked on PCMag’s hardware team, covering at various times printers, scanners, projectors, storage, and monitors. I currently focus my testing efforts on 3D printers, pro and productivity displays, and drives and SSDs of all sorts.

Over the years, I have reviewed iPad and iPhone science apps, plus the occasional camera, laptop, keyboard, and mouse. I’ve also written a host of articles about astronomy, space science, travel photography, and astrophotography for PCMag and its past and present sibling publications (among them, Mashable and ExtremeTech), as well as for the PCMag Digital Edition.

Read Tony’s full bio

Read the latest from Tony Hoffman