Samsung first revealed its SM951 PCIe SSD in Korea last year. The M.2 gumstick was billed as an NVM Express implementation at the time, but the drives that started rolling off the production line in January were instead tied to the aging AHCI protocol. Now, Samsung tells us that the NVMe version of the SM951 has entered mass production.
Like its AHCI twin, the SM951-NVMe has a proprietary controller with quad Gen3 lanes. The NVMe unit won't be bound by the queuing limitations and higher protocol overhead associated with its sibling, though. Performance should be better as a result, and the official specs bear that out. Samsung rates the drive for 2260MB/s with sequential reads and 1600MB/s with writes, a smidgen faster than the AHCI version. The random read specs are much higher: 300k IOps versus 130k IOps.
The press release doesn't quote random write rates, probably because they're nothing to write home about. HP's Z Turbo Drive G2 appears to be powered by the same Samsung hardware, and it's only specced for 100k random write IOps, a figure that wouldn't look out of place next to a high-end SATA drive. Intel's 750 Series NVMe SSD promises a much more impressive 290k IOps in its fastest configuration.
To be fair, the 750 Series is limited to desktop-style expansion cards and jumbo 2.5" drives. The SM951-NVMe comes in a much smaller form factor that's compatible with both desktops and notebooks. It should consume much less power than the 750 Series, and it also supports a special L1.2 standby mode that's claimed to reduce power consumption to under two milliwatts.
Although the SM951 family is built primarily for large PC makers, the AHCI variant is already available to consumers through some outlets, and the NVMe iteration is likely to follow suit. As with its predecessor, the drive comes with 128GB, 256GB, of 512GB of MLC NAND. This planar flash isn't as slick as the multi-layer stuff used in some of Samsung's SATA SSDs, but the company says it "plans to incorporate its next-generation 3D V-NAND technology into its NVMe SSD line-ups."