The ADATA Atom 50 is the company's newest value-oriented M.2 NVMe SSD with PCI-Express 4.0 support. Unlike the vast majority of Gen 4 drives, which are quite expensive, the Atom 50 comes at pricing that matches the price points of many Gen 3 SSDs: just $120 for the tested 1 TB version. The ADATA Atom 50 is the first drive using the new Innogrit IG5220 controller, which achieves much better performance than what I would have expected, especially considering it's a DRAM-less design. As flash chips, Micron's newest 176-layer 3D TLC is used. The lack of DRAM cache is a cost optimization, and it also helps with supply chain logistics—one less component to worry about.

Synthetic test results for the Atom 50 are good, in line with what you'd expect from a decent PCIe 4.0 SSD. Sequential read at low IO depth is especially good, reaching 5400 MB/s, which is faster than the Samsung 980 Pro and Crucial P5 Plus. 4K Random Write is also really good, especially considering we're dealing with a DRAM-less design here. Without looking at the actual PCB, I wouldn't have been able to tell that this is a DRAM-less drive, not from any of our tests. We've seen similar performance results from other modern DRAM-less drives, like the Samsung 980 non-Pro and WD Blue SN570. It seems controller vendors have figured out some new tricks on how to handle the challenge of a DRAM-less design. The XPG Atom 50 has support for the Host Memory Buffer (HMB) feature, which allocates some system memory to use as replacement for the DRAM cache. Technically, the Atom 50 can use up to 512 MB HMB, but Windows will max out at 64 MB unless you play with the registry.

While the synthetic results are certainly good, basing your buying decision on those alone isn't the best idea. Controllers have been optimized for synthetic testing using a mostly empty drive, a typical review scenario. That's why our real-life testing is so important. We're running the actual application, which hits the drive with much more complex load patterns. What's also important is that we're testing with the drive at 80% full, which makes things much more difficult for the controller because it doesn't have tons of unused flash to work its magic with.

Real-life performance numbers for the ADATA XPG Atom 50 are astonishing. It's the fourth-fastest SSD in our test group, faster than any PCIe 3.0 drive, faster than the ADATA Gammix S70, and just marginally slower than the best Gen 4 drives out there, with the Kingston KC3000 and Samsung 980 Pro merely 1% faster, and the WD Black SN850, the fastest drive we ever tested, is 2% quicker—at MUCH higher cost. Compared to PCIe 3 drives, the Atom 50 has around 5% higher performance, and compared to value NVMe drives, the gap widens to 15%; SATA drives are 25–30% behind.

Thanks to a large SLC cache paired with clever storage management, the Atom 50 has good sustained write performance, especially considering its positioning. When mostly empty, the drive will store incoming data as SLC first, which is very fast at over 4.5 GB/s, but consumes three times the storage because it fills each three-bit TLC cell with just a single bit. This mode is active until most of the drive is filled, 280 GB in SLC mode consume 840 GB of TLC capacity. Once that margin is crossed, the drive will switch into another mode which fills cells in MLC mode, storing two bits per cell, which is still very fast—2 GB/s. At the same time, a background process moves data out of the SLC cache into MLC or TLC, so that there's enough space for the incoming writes in MLC mode. Once 480 GB of data have been written, the drive starts writing directly into TLC, at 500 MB/s. Overall, this is a good result. Filling the whole 1 TB capacity completes at 800 MB/s on average, which is better than all value-oriented SSDs in our test group, but only roughly half of what we've seen on the best Gen 4 SSDs.

Thermal performance of the ADATA XPG Atom 50 is impressive. The Innogrit controller is a highly energy efficient design that doesn't put out a lot of heat. In our worst-case thermal loading test, we couldn't get the drive to throttle even when throwing tons of data at it with no airflow. ADATA does include an optional heatsink that's more of a heatspreader. While it's easy to install and drops temperatures quite a bit, I don't think there's much reason to do so given the stellar thermal performance. The heatsink is not preinstalled, probably to make it easy for people to fit the bare SSD onto any motherboard with an integrated M.2 heatsink.

Priced at just $120 for the tested 1 TB version, the Atom 50 is the most affordable PCIe Gen 4 SSD on the market that offers good performance. There are indeed similarly priced PCIe 4.0 SSDs available, but these use various older controllers that are not nearly as fast. People have been complaining about prices of PCIe 4.0 SSDs for a long time, and there's now finally an option that's just as affordable as the aging PCIe 3.0 drives out there. The only compromise is that the Atom 50 is DRAM-less, but that's impossible to notice due to various optimizations. Of course I wouldn't recommend putting this drive in a busy server with a write-heavy database of a several hundred GB, but such a workload is very difficult for all consumer drives. Another "issue" is that the largest capacity for the Atom 50 is 1 TB—no idea why. The PCB even has pads for additional flash chips, so I guess it's only a question of time until we see a larger version. ADATA had no details to share when I asked about upcoming versions with other capacities.

Thanks to its low price, the ADATA XPG Atom 50 is the best price/performance option available on the whole market today if you want a PCIe 4.0 drive. Noteworthy alternatives are the WD Black SN850 for $180—the fastest, if you have the money—and WD Blue SN570 for $90 or Kioxia Exceria for $85—if you want the absolute best value and can live with slightly lower performance. That's it, not much else can impress as much as these four drives.

What's very important to mention, and I confirmed this personally with ADATA, is that they guarantee that the Atom 50 will always come with the components that we tested: Innogrit IG5220 controller paired with 176-layer 3D TLC NAND flash from Micron. This will ensure peace of mind for many customers who've been burnt by various component-level changes on other SSDs.