Western Digital's new WD Blue SN580 is built using in-house components only. This is an important advantage compared to other brands that have to buy controllers from Phison, for example, and pair it up with NAND flash that they buy from Micron. There's not a lot of companies out there with the ability to source everything in-house: Samsung, Micron (Crucial) and Hynix (Solidigm) are the only other ones.

Under the hood, the SN580 is powered by a SanDisk 20-82-10082 controller and 112-layer 3D TLC BiCS5 NAND flash. While it would have been nice to see the newer 162-layer NAND flash, it makes sense from a cost perspective to use existing technology that's readily available. As expected, a DRAM cache is not included on the SN580, because it shaves a few dollars off the production cost—very important in this segment. Remember, we're talking about a sub-$50 1 TB drive here. Higher-end drives have a separate DRAM cache chip that stores a copy of the mapping tables of the SSD. This table helps the controller figure out where a piece of data is located; like most DRAM-less SSDs, the SN580 does use some of the host system's memory, though (HMB or Host-Memory-Buffer). The HMB size is 200 MB, which is more than the 64 MB that we're typically seeing on DRAM-less SSDs.

Synthetic test results of the SN580 are decent, certainly above most DRAM-less alternatives. While none of the test results are outstanding, they suggest that the SN580 is a very decent drive. Specifically for DRAM-less drives I've designed a special test that runs random writes over an increasingly large test area, to determine how much the lack of a dedicated DRAM-cache affects the controller. Here the WD SN580 can impress, it's the fastest DRAM-less drive we've ever tested, by quite a huge margin, especially when compared against drives with Phison and Innogrit controllers. At small work area sizes, the SN580 is more than twice as fast, with work areas of around 40 GB, that gap even increases to 400%! This is where the magic is—algorithms. Throwing more hardware at a problem is one solution, figuring out clever methods how to mitigate the lack of a DRAM cache is another way, which is more elegant and free of manufacturing cost increases (beyond the initial R&D).

Our extensive real-life testing with actual applications (not disk traces) and the drive at 80% full, confirms that the SN580 is an affordable SSD powerhouse. It is one of the fastest SSD's we've ever tested, despite the attractive price point. It basically murders all the other value-drives out there, claiming a spot right in the middle of the high-end drives. With performance that's virtually identical to Samsung 980 Pro, WD Black SN850, Solidigm P44 Pro, WD Black SN770 and Kingston KC3000 it's impossible to complain about performance. Remember, this is a DRAM-less drive, yet it excels at our consumer workloads, even with 80% of the disk filled! No doubt, there's better drives to use if you run a 500 GB SQL database in your enterprise server, but for consumers the SN580 is one of the best drives you can buy. Interestingly, the SN770, which seems based on similar components does end up a tiny bit faster, nothing you'd ever notice in real-life. It really makes zero sense to buy a QLC drive, or one of the other budget drives.

Just like all other modern TLC drives, the SN580 comes with an pseudo-SLC cache that absorbs incoming writes at high speed, but uses three times the storage to do so. Our testing reveals that the SLC cache is sized at 341 GB, which means the drive will fill all of its capacity in SLC mode first. This is a huge improvement over the SN570, which came with a tiny 12 GB cache only that got filled up in the blink of an eye. We were able to fill the whole 1 TB capacity at 600 MB/s, which is similar to other competing budget drives, maybe with the exception of the Team Group MP44L (1.45 GB/s) and the XPG Atom 50 (805 MB/s). So if you plan on writing a lot of data regularly, do prefer the MP44L.

WD does not include a heatsink with the SN580 and it's really not needed. While our worst-case thermal load testing shows that there's a tiny bit of thermal throttling, this won't be the case for typical usage. WD was smart to set the thermal throttle point very high, at 105°C, which provides enough headroom for workloads to finish, so the drive can cool down again. I'm surprised though that the thermal sensors are so inaccurate, they claim 88°C, while we've measured 106°C surface temperature. No big deal, still worth knowing if you plan on trusting software temperature readings. What helps to make the difference is WD's energy-efficient controller design, which means reads and writes result in lower heat output—good job WD.

The 1 TB WD Blue SN580 currently sells for just $45, which is an extremely attractive price point. At that price it is basically the most affordable SSD on the market that still gives you decent performance. Especially with the excellent performance, the SN580 is a no-brainer. Some competition comes from the WD Black SN770 ($50), Team Group MP44L ($47), Samsung 980 non-Pro ($50) and MSI Spatium M450 ($38). At the end of the day, the WD Blue SN580 is what I would buy, unless really every single dollar matters. It will be really hard to justify spending up to twice that amount of money just to get a high-end drive with DRAM. I just wish WD made a 4 TB version, which would certainly be attractive, considering how much SSD prices have come down.