The ADATA GAMMIX S50 Lite 2TB SSD Review: Mainstream PCIe Gen4

Conclusion

The ADATA XPG Gammix S50 Lite is the first SSD of its kind: a PCIe Gen4 NVMe SSD aimed at the mid-range mainstream segment of the consumer SSD market. Most Gen4 SSDs on the market were designed to go after the high end space, though the earliest such examples have now effectively been pushed down to mid-range by the arrival of a second wave of even faster Gen4 drives. By aiming for a more mainstream (and less expensive) role, the S50 Lite doesn't even try to make full use of the bandwidth offered by PCIe Gen4, and at its best it can only use a little bit of the extra speed over PCIe Gen3.

In fact, the S50 Lite is best understood by almost completely ignoring the fact that it supports PCIe Gen4; that feature can be viewed as simply a side-effect of the S50 Lite being a fairly modern design, so of course it should support the current IO standards. At heart, the S50 Lite is designed to be an affordable mainstream drive with the same general performance that required a high-end drive two or three years ago.

The S50 Lite is built around Silicon Motion's SM2267, their first PCIe Gen4 controller and the smaller, cheaper member of what is planned to be a broader family of Gen4 SSD controllers. We had originally hoped that SM2267 would allow drives like the S50 Lite to follow in the footsteps of the SK hynix Gold P31, bringing the benefits of a thoroughly modern 4-channel NVMe SSD to a broader audience. But the SM2267 only gets halfway there: it provides most of the performance we expect from a high-end 8-channel Gen3 drive, but since it's still a 28nm part we don't see the astounding power efficiency advantages that SK hynix delivered.

The S50 Lite also doesn't include the full amount of DRAM that high-end NVMe drives use, which hurts its performance on some heavier workloads. But that's more acceptable these days, since users with such workloads should be moving on to today's high-end Gen4 drives. (Side note: if ADATA is equipping the 1TB model with the same 1GB of DRAM that our 2TB sample gets, then the 1TB model probably avoids some of these performance pitfalls.) The result is that the SM2267 controller should be seen more as a reduced-cost replacement for the SM2262 family, and drives like the S50 Lite are aiming for a slightly lower market position than something like the SK hynix Gold P31.

Given the choice between the S50 Lite's nominal support for PCIe Gen4, or a well-rounded Gen3 drive, the answer is clear. Gen4 support on its own does not make a drive better, and there are plenty for Gen3 drives that offer better real-world performance and efficiency than the S50 Lite. In addition to the relative paucity of DRAM, the S50 Lite also suffers from small SLC cache sizes when the drive is mostly full. The fact that the S50 Lite supports a PCIe Gen4 host interface is almost completely irrelevant: at best it's barely able to exceed Gen3 performance, and it's unlikely to be used in systems providing a Gen4 x2 slot (which are likely to use even cheaper SSDs). It's good to see that SMI can ship a Gen4-capable controller, but the high-end SM2264 controller that we're still waiting for is the one that actually needs the Gen4 interface.

The pricing for the Gammix S50 Lite is unimpressive but also unsurprising. The drive has a bit of bling and can advertise PCIe Gen4 support, so it ends up priced close to the Gen3 drives from top-tier brands like SK hynix and WD, though with less of a premium on the 2TB capacity. It is at least clearly cheaper than the high-end Gen4 drives with 8-channel controllers, even the older Phison E16 models. Still, there are dozens of brands selling Phison E12S or SM2262EN-based Gen3 drives that will have equivalent or better real-world performance to the S50 Lite, but are more affordable. The cheapest of those models come with shorter 3-year warranties, which may not be worth the savings to some consumers.