Drivers in place, BIOS and connectors — not
One of the best things about NVM Express is that you don't have to worry about drivers showing up. Linux has had NVMe support since kernel 3.1; Windows 8.1 and Server 2012 R2 both include a native driver, and there's a FreeBSD driver in the works. When Apple decides to support NVMe, the latter should make it easy to port.
However, BIOS support is largely lacking. Without an NVMe-aware BIOS, you can't boot from an NVMe drive, though anyone with a x4 PCIe slot or M.2 connector can benefit from employing an NVMe drive as secondary storage. An NVMe BIOS is not a difficult technical hurdle, but it does require engineering hours and money, so it's unlikely it will stretch far back into the legacy pool.
Equally daunting for early adopters is the connection conundrum. Early on, you'll see a lot of expansion card NVMe drives using Gen 3 PCIe slots. That's because all 2.5-inch NVMe SSDs use the new SFF-8639 (Small Form Factor) connector that's been specially developed for NVMe and SATA Express, but is currently found only on high-end servers. An SFF-8639 connection features four Gen 3 PCIe lanes, two SATA ports, plus sideband channels and both 3.3-volt and 12-volt power.
There are adapters and cables that allow you to connect 2.5-inch NVMe SSDs to M.2, but as M.2 lacks a 12-volt rail, the adapters draw juice from a standard SATA power connector. The real issue with M.2 is that on Intel systems it's generally implemented behind the PCH (Platform Controller Hub), which features only Gen 2 PCIe. That's because the PCH lies behind the DMI (Direct Memory Interface) which is capped at 2GBps. You can see the problem.
Note that NVMe via M.2 isn't 3.3 times faster than SATA. But if you pay the money, you're going to want your SSD to be all it can be. At least I would. That means an expansion card drive until SFF-8639 connectors show up on consumer PCs.
NVMe SSDs actually showed up last summer with Samsung's 1.6TB MZ-WEIT10, which shipped in Dell's $10,000 PowerEdge R920 server. Gulp. Intel followed suit with the announcement of its pricy PS3600 and 3700 series NVMe SSDs, which are available in capacities up to 2TB. The first consumer NVMe drive to show up is Intel's 750. It's fast. Read our review.
The Current Outlook
Enthusiasts will want to take a hard look at Intel's 750. Most recent high-end motherboards will get firmware upgrades to support NVMe so you can boot from the drive. Most legacy mainstream boards will probably not. But our talks with Intel and other vendors indicate that the flood gates have opened, and you should see a torrent of NVMe support later in the year.
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