The Silicon Power UD70 is built by pairing 96-layer QLC flash from Intel/Micron with the Phison E12S controller—a combination we've seen on the Sabrent Rocket Q and Corsair MP400 before. Actually, all these drives use the same Phison reference PCB design—the biggest difference seems to be that the Silicon Power UD70 uses 512 MB of DRAM cache, whereas the Rocket Q has 256 MB and the MP400 1 GB. Averaged over our real-life testing suite, the UD70 delivers very decent performance that's comparable to most entry-level TLC SSDs, like the ADATA Falcon, Swordfish, and HP EX900 Pro. Compared to the Sabrent Rocket Q, the UD70 is 4% faster, but it's 2% slower than the Corsair MP400. Samsung's highly popular 970 EVO is only 3% faster, the fastest PCIe Gen 3 SSDs are up to 11% faster, and the difference reaches 16% with PCIe Gen 4. Compared to SATA SSDs, the performance uplift is around 15%, 40% if you compare against QLC SATA—definitely something you'll notice in everyday usage.

Synthetic numbers of the Silicon Power UD70 confirm our findings; the drive's strongest suit is its high write performance, both in sequential and random IO, which is the backbone for the good real-life performance results. QLC flash improves the capacity by storing four bits of data per flash cell instead of three like TLC and two like MLC. While that obviously brings with it cost savings, the drawback is that writing to QLC is much slower than writing to TLC or MLC. In order to hide this performance penalty, all QLC-based SSDs operate some of their capacity in SLC mode, which is extremely fast to write to, but uses four times as much space. On the UD70, Silicon Power has configured the drive to use all capacity in SLC mode first, up to 500 GB—a quarter of the 2000 TB QLC capacity, and only then will the drive start flushing SLC to QLC with a significant performance loss—like all QLC SSDs. In our testing, we could write to SLC at 3 GB/s, but writing to QLC operated at only 250 MB/s. This is not as big a deal as it sounds right now and doesn't mean that once you're 25% full, you're only getting 250 MB/s writes. Our real-life testing happens with the SSD at 80% full, and we still got very decent performance out of the UD70.

There isn't much to report on the thermal testing side, other than that we couldn't get the drive to thermally throttle, which of course is a good result. It's also good to see that there is no risk of thermal throttling, no matter what you throw at the SSD despite the lack of a heatsink. In this market segment, a heatsink would just increase cost too much—consumer workloads can't drive up temperatures that much anyway.

With a retail price of $210, the Silicon Power UD70 is one of the most affordable 2 TB M.2 NVMe SSDs out there. Competing QLC drives are more expensive; we have the Sabrent Rocket Q for $220, Corsair MP400 for $230, and Crucial P1 for $230. Out of those, the UD70 is the best deal—the performance differences are negligible. However, strong competition comes from various TLC drives around this price point or slightly above. For example, drives worth considering are the Team Group Cardea Zero for $205, ADATA Swordfish for $210, ADATA SX8200 Pro for $240, and HP EX950 for $250. Don't get me wrong, the UD70 is a very capable SSD that's great for light consumer workloads and a huge upgrade over any HDD-based setup, but for some use cases it simply makes sense to go with TLC instead of QLC. If Silicon Power could bring their pricing down a little bit more, to around $200, possibly below, it would suddenly become a tempting alternative to many 1 TB SSDs—spend just ~$50 to double your capacity with only a marginal performance hit in most workloads. Power users who write dozens of GB every single day should be looking at TLC SSDs, though, possibly PCIe Gen 4, at much higher pricing, of course.