With the P31, Hynix has entered the enthusiast SSD space with a truly impressive drive. Under the hood, the P31 uses only in-house components—everything is made by Hynix. Previously, only Samsung had this ability, which not only helps with engineering a good product, but is also more cost efficient. I don't know if Hynix plans to sell their controller to third parties or whether they will keep it in-house only. Selling the controller would definitely shake up things in the SSD space, which is currently dominated by Silicon Motion and Phison.

Synthetic numbers of the Hynix Gold P31 are very impressive. Random IO, mixed, read, and write are right up there, fighting it out with the best PCIe Gen 3 drives in our test group. The P31 "only" supports the PCIe Gen 3 interface, but is also more affordable than the newest Gen 4 flagships, which offer much higher sequential transfer rates. While vendors only want you to look at the sequential speeds, these only play a small role in real-life performance; random IO is more important for most workloads.

Our real-life testing suite goes beyond synthetics and runs the actual applications at 80% disk full, which is a more realistic scenario than a completely empty drive running a synthetic test. Real-life benchmarks are much harder to optimize for, too. Here, the P31 shows numbers that are so good I had to double check them to confirm everything was right. Hynix's P31 is the fastest PCI-Express 3.0 SSD we ever tested, beating famous drives like the HP EX950 by 3%, ADATA SX8200 Pro by 2%, and Kingston KC2000 by 2%. Another important data point is that on average, the P31 can match the real-life performance of Samsung's MLC-based 970 Pro. Last but not least, PCIe 4.0 drives with less powerful controllers, like the ADATA S70 and Gigabyte AORUS Gen 4, do fall behind the P31 despite their faster interface. Only the fastest Gen 4 SSDs can beat the Hynix P31: Corsair MP600 Pro by 1%, Samsung 980 Pro 2%, and WD Black SN850 3%. These are tiny differences that make it very hard to justify the price increase. On the other hand, if the majority of your workloads are sequential transfers, going PCIe Gen 4 can definitely make sense.

Sequential write performance of the Hynix Gold P31 is excellent, better than most competing drives. Filling the whole 1 TB capacity completed at 1.5 GB/s, which is the best PCIe Gen 3 TLC SSD result we ever saw. With 85 GB, the pseudo-SLC cache is reasonably large, sufficient for nearly all workloads, I still would have wished for a bit more. SLC cache usually operates as a percentage of the drive's free space, so as the drive fills up, SLC cache size goes down slowly. That's why I feel an SLC cache of around 150 GB (on an empty 1 TB drive) would have been slightly better. Once again, we're testing our real-life benchmarks at 80% disk full, so the SLC cache size is already taken into account for our real-life performance results, which are impressive. Of course, momentarily stopping the write activity will have 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.

Unlike some other high-end M.2 NVMe SSDs, the Hynix Gold P31 does not come with a heatsink preinstalled, and it doesn't need one. Even in our worst-case thermal loading test did we not even see a hint of thermal throttling—very impressive. This clearly sets the drive apart from Phison and SMI-powered drives, which do run into thermal throttling in some situations. The magic lies in the controller, which must be a very energy-efficient design—lower energy consumption means less heat output, which avoids throttling. What I would also like to praise Hynix for is that their thermal reporting is VERY accurate. This isn't standard. We've reviewed M.2 NVMe drives before that reported 30°C below actual temperatures.

Priced at $135 for the tested 1 TB version, the SK Hynix Gold P31 is very reasonably priced, especially considering how fast it is. Around that price point, you'll also find its strongest competitors: the ADATA SX8200 Pro ($130), Kingston KC2500 ($135, the KC2000 is currently more expensive), and HP EX950 ($140). These prices are changing almost daily, so do keep an eye out for discounts. Still, Hynix is clearly pricing their product competitively, unlike Samsung, who just relies on the brand name and want $150 for the slower 970 EVO+. If you only care about price/performance and are happy to sacrifice some performance for better pricing, then entry-level value M.2 NVMe SSDs could be an option; these retail at around $100 and are not that much slower. Last but not least, if you want the fastest, then PCIe Gen 4 it is. Here your only options vs. the Hynix Gold P31 are the Corsair MP600 Pro ($210), Samsung 980 Pro ($210), and WD Black SN850 ($250). It won't be easy to justify that price increase for a few percent higher performance.