WD Black SN850X 8TB NVMe SSD review

That’s eight terabytes of memory on a single PCIe SSD. Seriously. We’ve come a long way since the M.2 solid-state storage concept, right? This pretty, elegant little thing from Western Digital pushes the boundaries of what’s currently possible when it comes to the amount of space you can fit on a single flash drive. It is nothing low of an engineering marvel. But this raises some pretty significant questions. Not only from a stereotypical hardware review perspective, but also from a exploit case perspective. In low, who is this for? How can you justify 8TB of storage in an age of blazing-fast internet speeds and near-hassle-free cloud storage solutions?

WD’s SN850X SSDs are also not fresh to the market. We reviewed WD’s SN850X series when it first debuted globally in October 2022. But Joe Public has finally received the 8TB capacity upgrade from the company. Complete with an improved controller, much denser NAND memory and a really large price tag.

In terms of core technology, the 8TB variant uses a proprietary Sandisk controller built on the Triton MP16+ B2 platform (the same one found in the original lineup). It combines this with Kioxia’s 162-layer BiCS6 TLC NAND memory, housed in four separate packages on a flash drive. The whole thing is then backed by a solid DDR4 board so that everything ties together nicely, and of course it’s all packaged in the ever-faithful M.2 2280 case (though it’s double-sided) along with an optional heatsink if you need it.

As for cost, well, since the 8TB model first launched, WD has rather intuitively hit it over the head with a pretty large price-cutting hammer. You can buy one of these now in the US for around $650 (it debuted for $850). That’s a clever move, considering two 4TB WD SN850X drives will only save you a total of $600. WD basically has something to do with this issue. At the same time, it must maintain an inventory of older units without negatively impacting sales when a fresh model is launched. Expect these prices to fluctuate quite often, especially during sale seasons.

When it comes to performance, the SN850X 8TB model is quite impressive. In my tests, subsequent data on Crystal Disk Mark was around 7,100 MB/s reading and 6,590 MB/s writing. Both decent for a 4.0 drive and about what WD says it will compete with, although in both cases slightly lower than advertised. Random 4K, however, is more of a cause for concern. With read speeds of just 72MB/s and write speeds of 298MB/s, it’s one of the slowest contemporary PCIe 4.0 drives I’ve tested, second only to the Samsung 990 Evo Plus.

This is a bit of a pain, especially if you want to exploit it for a game drive.

Unfortunately, much smaller SSDs like Crucial’s P310 or WD’s SN770M fall low in this regard. The SN770M achieves speeds of 79 and 305 MB/s, respectively, and the P310 also manages speeds of 76 and 315 MB/s. Even WD’s Blue SN5000, a much cheaper alternative to Kioxia’s 162-layer QLC technology, managed speeds of at least 80MB/s for 4K reads. This didn’t exactly translate into our gaming tests, remember that the Shadowbringers Final Fantasy XIV benchmark achieved a respectable load time of 7.283 seconds on average.

These lower read and write speeds are likely due to the raise in latency resulting from the SN850X 8TB using four NAND chips instead of two or even one found in alternative drives. This then slows down the overall read and write speeds across the board, albeit slightly. This also aligns well with other marketing materials for the SN850X’s capacity options, as they are all listed as capable of 7,300 MB/s reads, rather than 7,200 for the 8TB.

This is probably also a large reason why WD chose Kioxia’s much denser NAND to make 8TB easier to exploit, considering it’s much faster but still not enough to achieve the same speeds as its predecessors.

Testbed for PC gamers
Processor: AMD Ryzen 9 9900X | RAM: 64 GB (2×32 GB) Team Group T-Create Expert DDR5 @ 6000 C34 | Graphics card: Nvidia GeForce RTX 4080 Super | Motherboard: ASUS ROG Strix X870E-E Gaming WiFi | CPU Cooler: Asus ROG Ryujin III 360 ARGB Extreme | Power supply: 1200W NZXT C1200 (2024) 80+ Gold | Chassis: a geometric model of the future 5

The bigger question you need to ask yourself is: is it worth it? From a purely practical point of view, having such a drive with a capacity of 8 TB (7.27 TB in Windows for those curious) is a bit of a risk.

As a manufacturer, if you want your SSD to become one of the best SSDs available at any given time, reliability and durability are key elements on this journey. And I’m not saying that WD doesn’t have a reputation for these two things; it really is. However, like all SSDs, these drives have a life cycle and data cells that can become damaged and degraded. Something may go wrong.

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If you store all your games, media or significant documentation solely on one 8TB drive without a proper backup solution and everything goes wrong or your house is struck by lightning and everything fries, this is a fatal error that can cost you significantly. more than the value of the disk itself.

From a gaming perspective, is the price worth the convenience gained? If you already have a solid internet connection, downloading, playing, deleting and re-downloading in random order is also not that challenging of a task. Which again hits the SN850X 8TB a bit on the nose. Sure, if you spend days downloading the latest expansion for Diablo IV, it might be worth it, but even then, you’ll definitely be better off with the much cheaper, slightly faster, dual 4TB PCIe 4.0 drives instead. It’s just a lot more practical, at least if your motherboard supports it.

But that aside, what’s fascinating about this drive isn’t what it represents now, but what it means for the future.

When the first 4TB variant launched in 2022, it had an MSRP of $700. Today, at the time of writing this review, you can get it for just under $292. This means the price will drop to just 41% of its launch price within two years. This is a radical price reduction and the same applies to the competition. With this in mind, will 2026 finally be the year we get 4TB SSDs for $140 and this 8TB solution won’t seem so outlandish? I hope, that’s for sure, and I hope it all becomes moot.