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The WD Black SN770M is a unique SSD, designed very specifically for expanding the storage in a wide variety of handheld gaming PCs, and given the limited form factor it performs admirably. Although relatively slow for a PCIe 4.0 drive, it continues to impress in the areas that matter and doesn’t entirely break the bank as it does so.


  • Perfect for handheld gaming PCs
  • Impressive performance given no cache
  • Decently priced


  • Can get quite hot under load
  • Limited space means no cache

Key Features

  • M.2-2230 Small Form FactorThe WD_Black SN770M is perfectly sized for inclusion in any Steam Deck, ROG Ally, or equally expandable handheld gaming PC.
  • Well-rounded PerformanceDespite having no cache on the SSD itself, the WD_Black SN770M continues to perform admirably with otherwise limited space.
  • Solid Endurance Rating600 TBW might not sound like much, but given this drive is predominantly going to be used for gaming and only gaming, that, and its 5-year warranty are a solid combo.


Western Digital’s WD Black SN770M PCIe 4.0 SSD is a drive designed with one very specific purpose in mind, and that’s to upgrade your Steam Deck or ROG Ally’s expandable storage.

With that caveat comes some serious limitations when it comes to space. In fact, it’s so tiny, this form factor was initially designed for use as WiFi add-in cards, rather than something like an M.2 SSD.

Still, Western Digital hasn’t let that hold them back, and despite the lack of space, it managed to cram in enough hardware to get some seriously chunky performance out of that tiny form factor. It’s not without fault, and there are of course caveats to building any SSD like this, but nonetheless, it represents a significantly impressive engineering step.


  • Zero cache on board
  • Fairly low-density NAND
  • Unique Sandisk controller

The big talking point here is that form factor. When it comes to M.2’s we define the size by the numbers that come after the M.2-”XXXX” bit, so typically, you’ll have an M.2-2280, the 22 denotes the width (so in this case 22mm) and the 80, would be the length (again 80mm). In the SN770M’s case, it’s a 2230, so yup, there’s 30mm of space total to play with. 

the back side of an WD_Black SN770M 1TB M.2 PCIe 4.0 SSDWD_Black SN770 NVMe SSD on wooden surface.
Image Credit (Trusted Reviews)

Western Digital’s crammed that tiny footprint with two chips total. A controller, Sandisk’s 20-82-10081-A1. Sandisk is now a part of Western Digital so that’s not entirely surprising as it does help to keep overheads down. But sadly, it does mean we don’t know a whole lot about it. It clearly supports TLC and the PCIe 4.0 form factor, but WD’s keeping its lips sealed otherwise.

Aside from that, the biggest omission by far (again to make space for the controller and the singular NAND chip) is the lack of any DRAM cache whatsoever. Yup, by default there’s nothing to help shimmy this drive along a touch. Particularly for small file transfers.

Storage Capacity
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That means pretty much all of the performance comes from the NAND itself. WD has partnered with a company called Kioxia and is utilising its 112-Layer TLC NAND as a result. That’s a fair bit less dense than the 176-layer and 232-Layer TLC Micron currently has available, which, combined with the cache does seem to limit performance somewhat, but given the limitations at play here, that’s again somewhat to be expected regardless of what NAND is in use.

Test Setup

Typically whenever I test SSDs they all get put through the same ringer. Each and every one of them is placed in my test system, usually in the top-most PCIe 5.0 slot, in a top-tier motherboard with a seriously quick CPU as well.

This helps eliminate any bottlenecks, and gives everyone an equal playing field, with most SSDs stripped of their respective heatsinks and placed directly under the thick weighty aluminium block Asus includes on the board I use.

I’m still following the same basic principles with our tiny WD Black SN770M, but with one slight caveat, I’ll also be speaking very specifically about the temperatures under load of some of these devices as well.

You can find the full test bed specs below:

  • CPU: Intel Core i7-14700K
  • Motherboard: ASUS ROG Maximus Z790 Dark Hero
  • GPU: Gigabyte GeForce RTX 4080 16GB Aero OC
  • RAM: 32GB (2x16GB) Corsair Dominator Titanium DDR5 @ 7200
  • Cooler: Corsair iCUE Link H150i LCD Liquid CPU Cooler
  • PSU: 1200W Corsair RMx Shift 80+ Gold PSU
  • Case: Hyte Y70 Touch

For the tests themselves. We run a mix of both synthetic and real-world performance benchmarks across all the drives. For synthetic that predominantly starts with Crystal Disk Mark 8 in its default configuration, followed by PC Mark 10’s Quick System Drive and Data Drive benchmarks as well for some more generalised index results.

WD_Black SN770M 1TB M.2 PCIe 4.0 SSD tested in a PCWD_Black SN770 NVMe SSD installed on a computer motherboard.
Image Credit (Trusted Reviews)

As for the real-world side of things, I’m utilising two primary tests on this front. The first of those is Final Fantasy XIV’s in-game benchmark. You can actually place this directly onto the SSD in question, and run it straight from the drive, with the benchmark giving you load times for each scene, and an overall average. The second real-world test is a raw file copy test. Simply put, we grab a stock copy of Red Dead Redemption II, copy it to the drive in question, then make a second copy of that copy, onto the drive as well, timing how long it takes to complete.

Finally, we also calculate a number of indices based on the value you’re getting per $ spent across sequential performance, random 4K performance, and of course gigabytes per $ as well. Oftentimes you might see a drive perform poorly compared to a number of our competitor drives, but if it’s priced accordingly, that could very well make it a far more attractive offer if you’re on a budget, and would rather spend your hard-earned cash picking up a better GPU instead.


  • Struggles in both sequential and random 4K
  • Sequentials generally topped out at the 5.2 GB/s mark
  • SSD can get really hot

Western Digital’s WD Black SN770M is a curious little thing. One quick look at the benchmarks and you can see that it’s not quite a top-tier PCIe 4.0 drive – in fact, it struggles in both sequential and random 4K quite considerably. Now you do have to bear in mind that it is limited by form factor, as well as temperature because of it, and thermal throttling.

Sequentials generally topped out at the 5.2 GB/s mark, well below some of our other PCIe 4.0 drives tested, including Crucial’s, now three-year-old, P5 Plus, which managed 6.5 GB/s and 5.1 GB/s respectively. Random 4K performance, however, was better than the P5 with the SN770M scoring 77 and 267 MB/s respectively there, versus 62 and 188, although compared to something like Adata’s Legend 960 Max, at 76 and 286, it still didn’t quite keep up. Now to be fair, I’m comparing a full-sized drive to a 2230 with the 960 Max, but the Legend clocks in at $85 RRP versus the SN770M’s $110 RRP.

Real world performance is where the drive struggles however, with Final Fantasy XIV’s load time falling in at 9.01 seconds, versus the P5 Plus’s 8.04 and the Legend’s 8.72. Real world file copy was a bit better than the P5 Plus, hitting 57.69 seconds, but still wasn’t close to something like the Legend’s 45.58 seconds sadly.

The big caveat, however, is the temperature because oh boy can this SSD get hot. Throughout my benchmarking runs, the max temp topped out at an impressive 89°C, according to HWMontior. That is staggeringly warm, particularly given that even the hottest of the hot PCIe 5.0 drives were only topping out at 72°C – 78°C across my testing, and most PCIe 4.0 drives sit comfortably at the 60°C mark.

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Should you buy it?

You should buy if you’re looking to upgrade your Steam Deck

The WD Black SN770M is a fantastic choice for those looking to upgrade their Steam Deck or ROG Ally’s internal storage.

You should not buy if you want an SSD for anything else

If you’re not limited by the 2230 form factor, then there are a far better array of PCIe 4.0 drives out there, for a lot less, that perform far better.

Final Thoughts

The WD Black SN770M is an incredibly unique SSD. Without a doubt, what WD has achieved with the form factor is nothing short of impressive. If you’re after some solid PCIe 4.0 performance, and extra capacity for your handheld PCs then it’s a perfect fit.

That said, it does come in at a higher price than some of its competitors from Sabrent or Corsair, particularly the Rocket 4.0 and MP600 Mini respectively. If you’re looking for some of the best SSDs for your PC though, this isn’t it. The Crucial T500 will serve you far better, for double the capacity, with superior performance, and without breaking the bank.

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How we test

Each SSD we test utilises a mix of both synthetic and real-world benchmark tests. On top of that, we also use a number of price-to-performance metrics, and monitor temperature and power-draw to determine the long-term stability and cost-effectiveness of the drive.

Each SSD is installed in our dedicated test system for benchmarking and analysis.

Power draw and temperatures are monitored throughout the testing process.


Is the WD Black SN770 good for gaming?

It’s not the fastest SSD on the market for gaming performance, but due to its unique form factor, it’s still a fantastic option for Steam Deck or ROG Ally owners who want to expand the storage. It will offer far better performance than a MicroSD Card.

Does WD Black SN770 have a heatsink?

No, the WD Black SN770 does not come with a heatsink.

Trusted Reviews test data

CrystalDiskMark Read speed
CrystalDiskMark Write Speed

Full specs

Storage Capacity
Release Date
First Reviewed Date
Model Variants
Storage Type
Read Speed
Write Speed
Heatset included?

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