Technology & Positioning
With the E31, Phison is introducing their second PCIe Gen 5 controller for the consumer space. While the high-end E26 will still be around as the flagship, the E31 is designed as lower-cost alternative that still achieves good performance, but at a lower price point. One of the major requirements for that is DRAM-less operation, because it lets SSD vendors save some cost and design complexity. The DRAM cache does not store your data, it stores the mapping tables of the SSD that tells the controller where to find a certain piece of information. On DRAM-less SSDs, a small portion of the system's main memory can be used for the mapping tables. The Phison E31 uses 64 MB for that, similar to what other competing controllers use. Phison's engineering sample drive comes with Kioxia 218-layer 3D TLC NAND, but I'm sure it's possible to build these drives with Micron NAND, too, probably YMTC as well.

Synthetic Performance
Phison are masters of optimizing their controllers for typical synthetic reviewer workloads on a mostly empty drive, and the E31 is no exception. In our synthetic testing, the drive shows impressive numbers that are among the best we've ever seen, topping even the E26 Gen 5 controller flagship in random IO. Phison did a great job eking out additional IOPS at the highly important low-threaded random IO workloads, because that's what matters most for real-life interactive workloads. I also like that 1M sequential mixed is greatly improved, which is very important, because it applies directly to file copy operations on the same drive, which read and write data at the same time. Sequential read and write is a little bit lower than on the E26 high-end drives, especially at low queue depth, because there's only four flash channels available instead of eight. When running with sufficiently high parallelism, the E31 ES drive reaches over 10 GB/s write and 9 GB/s read, which is a definite improvement over what Gen 4 drives can achieve.

Real-Life Performance
Our real-life testing is designed to run actual real applications, not disk traces that compress time by assuming infinitely fast hardware and software. We're even running those tests with the drives filled to 85% capacity, not empty. This approach puts additional pressure on the various algorithms and the SLC cache, just like in real-life. Here the Phison E31T ES does well, and ends up as the second-fastest drive in our test group, a tiny bit faster than the best Gen 4 drives, and 3% slower than the Corsair MP700 Pro. Overall I have to admit I'm a bit disappointed, because the drive isn't offering a noteworthy performance improvement over Gen 4 drives, except when it comes to sequential transfers. The next paragraph talks about performance when the SLC cache is exhausted, maybe that's a contributing factor affecting our real-life tests, because the drive is 85% full, which means there's not a lot of SLC cache left to work with. You also have to consider that this is an engineering sample, so it's likely that Phison and its partners will find additional performance as they get closer to final mass production release. Don't get me wrong, the E31 isn't slow at all, rather the opposite, it worked through our workloads at impressive speed, and with 100% stability.

SLC Cache / Sustained Performance
Phison's ES drive is configured with an SLC cache size of 404 GB (or 60% in SLC mode), which is enough to soak up nearly all bursts of write activity. Once the SLC cache is exhausted, transfer rates drop quite a bit, to 1.4 GB/s and there's a second drop to 700 MB/s if you keep hammering the drive. Filling the whole 2 TB capacity completed at 1.0 GB/s, which is a bit lower than expected. Most mid- and high-end Gen 4 drives do better than that.

Power Consumption / Heat
Thermals of Gen 5 drives have always been challenging, with all either requiring an active fan-cooled solution, or a huge heatsink, or both. One of Phison's development focuses was to lower heat output, which requires better energy efficiency. The new E31 is fabricated using a 7 nanometer process at TSMC Taiwan. Our power consumption testing shows that efficiency is truly stellar, it's the best drive we ever tested, beating even the Maxiotech MAP1602 by a small margin. In idle, power consumption is still pretty high though with 2 W, but that's not that big a deal, because it applies to desktop scenarios only. In a laptop config, the drive can reach its lowest ASPM power state easily, and uses only 0.074 W, which will help extend the battery life of laptops. With a maximum power draw of 5 W, the drive runs at less than half the power of the E26—very impressive. You still need a decent heatsink, the bare drive throttled fairly quickly with a stress-test workload. Lighter consumer workloads should run fine without a heatsink, and a bit of throttling should be barely noticeable. Even when throttling, the drive was responsive and achieved solid performance of 3 GB/s—nice! We also tested with a big passive heatsink and that avoided throttling almost completely, a major difference compared to the high-end E26 based Gen 5 drives, which really need active cooling.

Pricing & Alternatives
Pricing of the Phison E31 is completely unknown at this time, but since it's a cost-optimized Gen 5 solution, pricing must be lower than that of the E26 flagship drives, which currently sell for slightly above $200. That basically means that the E31 drives have to sell for less than $200. At the other end of the spectrum you have the top Gen 4 drives like the Samsung 990 Pro ($170), WD SN850X ($155) and of course the MaxioTech MAP1602 drives like the Lexar NM790 ($150). I guess that means pricing has to end up at around $175 to make sense. At this price point I could see people betting on the higher transfer rates willing to spend the extra cash, probably also for the bragging rights, and they don't have to compromise on noise levels of their rig, because no active cooling is needed. In the past weeks we've been testing new controller designs from Innogrit and Silicon Motion, so the Gen 5 SSD space will see some more action in the coming weeks and months.

Awards were not considered due to this being a preview