Samsung’s 990 EVO SSD is a PCIe gen 4 and 5 hybrid

Samsung has launched a hybrid gumstick SSD, the 990 EVO, which supports both PCIe gen 4 and 5.

The consumer-grade SSD EVO line started with the 840 EVO in 2013, with its SATA interface, 2.5-inch format, and TLC NAND, and progressed through 860 and 870 generations to the M.2 gumstick format. The 860 used 32-layer 3D V-NAND and then 64-layer, while the 870 EVO jumped to 128-layer NAND. After that it stepped up to the PCIe gen 3 interface with the 960 EVO in 2016. This provided a performance boost and was followed by the 970 EVO Plus.

Now Samsung has adopted a combined PCIe gen 4/5 design but with restrictions affecting its PCIe gen 5 performance. 

Samsung EVO IOPS
Chart showing how random read and write IOPS change across Samsung EVO drive generations

The drive comes with 1 or 2 TB capacities on a single sided M.2 2280 card. In its PCIe gen 4 guise it has four lanes and supports NVMe v2.0. The performance maxes out at 700,000/800,000 random read/write IOPS with a 5,000 MBps sequential read top speed and 4,200 sequential write top speed.


Samsung EVO sequential read/write bandwidth
And how sequential read and write bandwidth changes across Samsung EVO drive generations

The IOPS is nothing special with plenty of other PCIe gen 4 M.2 card drives exceeding 1 million IOPS. Ditto the sequential bandwidth. 

The oddity is that these performance figures don’t change when using the PCIe gen 5 interface. That’s because there are only two gen 5 lanes. Although each gen 5 lane should have twice the bandwidth of a PCIe gen 4 lane, the halving of the lane count means the overall performance doesn’t change at all.

This does mean the drive could be used in a gen 4 PCIe laptop now and in a gen 5 model later. That may be convenient for some but the drive’s performance is lackluster compared with other PCIe gen 5 M.2 SSDs. For example, Seagate’s FireCuda 540, with the same capacity levels, offers 1.5 million random read and write IOPS, and 10,000 MBps for both sequential reads and writes. Crucially, it has four gen 5 PCIe lanes, not just two.

Moving away from raw performance, we note that the 990 EVO uses its host’s DRAM as a buffer and has an onboard SLC cache for faster data IO – just as well as without that its performance would be even worse. Samsung says the 990 EVO has faster performance than the 970 EVO and, considering the PCIe bus level jump, so it should. However, view this 990 EVO as a PCIe gen 4-class drive that masquerades as a gen 5 PCIe drive because, in our opinion, it doesn’t deliver on the standard’s potential.

Samsung says it uses TLC flash but doesn’t reveal the drive’s layer count. Tech PowerUp reckons it’s a boosted gen 6 V-NAND with 133 layers instead of the standard 128.

The 990 EVO has a Samsung controller and a 0.3 drive writes per day endurance for its five-year warranty, meaning 600 total terabytes written for the 1 TB model and 1,200 total terabytes written for the 2 TB version. It supports 256-bit AES and TCG/Opal v2.0 encryption. The drive costs $124.99 for 1 TB and $209.99 for 2 TB.