When the Lexar NM620 was first announced, it wowed the whole industry—Longsys (Lexar's parent company) has built their own SSD flash controller! Looking a bit deeper, it turns out the controller is a rebranded Innogrit IG5216, probably with optimized firmware. Still, it shows that Lexar is definitely looking to go beyond the beaten path of using SMI and Marvell controllers. This is actually our first review for the Innogrit IG5216 controller, which turns out to offer very decent entry-level performance to build value-oriented DRAM-less SSDs. No experiments were made with the NAND flash, which is well-tested Micron 64-layer 3D TLC.

To reduce manufacturing cost, Lexar isn't including a DRAM cache chip on the NM620. DRAM on an SSD is used as fast temporary storage for the drive's internal mapping tables, which translate between physical disk addresses as seen by the OS and the actual location of where the data is stored in the flash chips: "which chip, at which location." Using DRAM has a speed advantage as it operates much faster than flash, but it's a cost/performance trade off. A 1 TB SSD typically uses 1 GB of DRAM, which costs a few dollars. If you can save that, you'll be able to position your drive more aggressively, leading to more sales, or you'll enjoy higher margins. The disadvantage is that random IOPS performance is lower because the controller has to access the flash more often to process the mapping tables. For nearly all consumer workloads, random write performance over a large area doesn't really matter, as our benchmarks show. Consumer workloads are very read-heavy anyway, and if writes happen, they are localized over a relatively small area, which is exactly why DRAM-less SSDs were invented.

Averaged over our real-life test suite, we see the Lexar NM620 competing with entry-level NVMe SSDs like the ADATA SX6000 Pro, ADATA Falcon, HP EX900 Pro, and WD Blue NVMe. It's also offering performance similar to QLC SSDs like the Sabrent Rocket Q and Crucial P1. I am a bit surprised that the Lexar NM610 beat the NM620 in several tests, though. Looks like the Silicon Motion SM2263 controller works a bit better with certain workloads. Only doing synthetic tests would suggest the opposite, which is why we test real-life applications and games with the drive filled to 80% of its capacity.

Compared to SATA SSDs, the Lexar NM620 will be around 15% faster, even 40% when you compare against SATA QLC SSDs from Crucial and Samsung. The fastest PCIe Gen 3 SSDs in our test group are up to 10% faster than the NM620. This year, we've seen a push for SSDs with PCI-Express 4.0 support—these are up to 16% faster than the NM620 on average—not a lot considering how expensive these new SSDs are.

With an SLC cache size of 208 GB, the NM620 is well equipped to soak up even the largest bursts of write activity. As long as the pseudo-SLC cache has capacity available, writes will complete at an impressive 3 GB/s. At some point, with heavy write activity, the SLC cache will be exhausted and speeds drop to around 800 MB/s—still faster than any SATA SSD. If you still keep feeding data into the SLC, it will drop to around 300 MB/s. Considering the positioning of the NM620, I think it's highly unlikely that consumers and entry-level users will run into these limitations. Also, 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.

Thermals are fine, no throttling despite the lack of a heatsink, which really isn't needed in this market segment anyway. The thermal reporting on the SSD is extremely optimistic, though. We measured almost 90°C using a thermal camera, when the software readings claimed 67°C. Not a big deal, just something you might want to be aware of if looking at sensor data is your thing.

With a price of around $160, the Lexar NM620 is simply way too expensive. It's even more expensive than some of the fastest PCIe 3.0 SSDs out there. Just to put things into perspective, the ADATA Falcon and Swordfish cost around $100, and the WD Blue NVMe $105. There's also plenty of 1 TB QLC drives for around $110 with similar performance. High-end M.2 NVMe drives like the HP EX950 and Kingston KC2500 cost $130 to $140, which is still cheaper than the NM620 and significantly faster. PCI-Express 4.0 SSDs might be faster in theory, but I find their price increase hard to justify from a price/performance perspective. Looking at the physical design of the NM620 I have no doubt Lexar has plenty of headroom for discounts. I'd say a realistic price is around $100, at which point I would definitely recommend it simply for the outstanding price/performance. Such a price point could do real damage to offerings from the big players, like Crucial and WD. Lexar hinted at upcoming promotions in the beginning of May, which could help tip the price/performance ratio towards the NM620.