The ADATA XPG Gammix S70 uses a flash controller by Innogrit—a company founded by ex-Marvell staff who decided to engineer their own SSD controller. Previously, the chips from Innogrit were limited to the low-end and mid-range segment, but with the new IG5236 Rainier controller, they want to change that. The new controller has everything enthusiasts are looking for: TLC with SLC caching, support for DRAM cache, and eight flash channels. The other components on the XPG Gammix S70 are four 3D TLC flash chips, most probably made by Intel/Micron, and 2 GB of fast DDR4-3200 DRAM for the mapping tables.

The PCI-Express 4.0 interface has become mainstream due to the success of AMD's Ryzen processors. Intel will support PCIe 4.0 with their upcoming Rocket Lake CPUs, which should help the push for PCIe 4.0 SSDs. You can also pair these drives with "Ice Lake" or "Tiger Lake" notebooks to have them work at maximum speed. Some more value-oriented PCIe Gen 4 drives, like the XPG Gammix S50 Lite I reviewed a while ago, use a controller with only four flash channels, which creates a bottleneck. Thanks to the Innogrit eight-channel controller design, this is not the case on the Gammix S70—we're seeing transfer rates of over 7 GB/s read and over 6 GB/s write.

When looking at the synthetic results of our test suite, one has to be impressed. The Gammix S70 has a higher Random IOPS rate than the Samsung 980 Pro and WD Black SN850, only the MP600 Pro is a tiny bit faster. Random writes and random mixed results are also fantastic. In our sequential read performance test, the Gammix S70 is actually the fastest drive we ever tested, and the other sequential test results are incredibly high, too.

If our review stopped here, I'd say this drive is at least as fast as the Samsung 980 Pro, WD Black SN850, and Corsair MP600—possibly even faster. But we also have our extensive suite of real-life tests, which run actual applications with the drive at 80% filled capacity, a highly realistic scenario. Here, things are much different. It seems the Innogrit controller has been heavily optimized for synthetic benchmarks on a nearly empty drive—just the way most SSD reviewers conduct their testing. When averaged over all our tests, the XPG Gammix S70 ends up 5% behind the Samsung 980 Pro and WD Black, which is a fairly large gap. This doesn't mean the drive is slow in any way, it matches the best PCIe Gen 3 drives in our test group, like the HP EX950, Kingston KC2000, and ADATA SX8200 Pro. Considering where Innogrit is coming from, this is a huge achievement, and I have to applaud their efforts. Compared to SATA SSDs, the performance uplift is over 20%, almost twice as fast as Samsung 870 QVO and Crucial BX500.

Owing to a large pseudo-SLC cache, sustained write performance of the Gammix S70 is good, filling the whole drive completes at 1.2 GB/s on average. When the cache is empty, this process runs at over 5 GB/s until the SLC cache has been exhausted. When the SLC cache is full, writes still run at around 1 GB/s, which is sufficient for nearly all scenarios. Competing drives are considerably faster here, though. The Samsung 980 Pro fills the whole drive at 1.9 GB/s, and the WD Black SN850 handles that test at 1.6 GB/s. Of course, momentarily stopping the write activity has the SLC cache free up capacity immediately, so full write rates are available as soon as you give the drive a moment to settle down.

Because of the large preinstalled heatsink, thermals are no problem on the Gammix S70. The highest temperature we measured in our stress test was 76°C—cooler than nearly all other high-performance SSDs. ADATA engineered a great attachment mechanism for the heatsink. While other vendors use some sort of sticky thermal tape, the pressure of ADATA's heatsink is much higher because of a clamped design with two screws, which improves heat transfer. The thermal sensor on the Innogrit controller also seems to be more accurate than competing chips as the difference between software-reported and actual temperatures is only minimal.

ADATA wants $400 for the 2 TB version of the Gammix S70—too expensive considering our real-life performance results. For $400, you can get the Samsung 980 Pro, which is the faster drive in every realistic scenario. Current PCIe Gen 3 drives are also strong competition for the Gammix S70. While their sequential transfer rates might not be as impressive, that won't make enough of a difference in real-life. Good options here are the HP EX950 2 TB ($245) and ADATA SX8200 Pro 2 TB ($240), at almost half the price, both are definitely worth considering. I still think ADATA XPG has a player here if they can bring the price down significantly—to below $300, which would have the drive sit in that huge void between current Gen 3 drives and the leading Gen 4 drives, making it an attractive option for many.