SilverStone has just announced its ECM20 expansion card, with the aim of bringing at least near-full M.2 SSD support to older systems. The card has one slot each for the two main flavors of M.2 SSDs, and installs in a PCI Express x4 slot on your PC’s motherboard.
The "B key" slot on the ECM20 will take a SATA 6Gbps-supporting M.2 SSD, with a SATA connector on the ECM20 plugging into one of your board’s SATA ports. Meanwhile, the "M key" slot supports PCIe M.2 SSDs. Assuming the ECM20 is attached to a PCIe 3.0-supporting x4 (or x16 physical) slot, that’s 32Gbps of headroom for the latest drives.
Naturally, there are some caveats with the M-key slot. The bandwidth is limited to 16Gbps if you use a PCIe 2.0-only board slot, and both your board and OS need to support NVMe to use PCIe drives as boot drives. While it doesn’t solve the latter point, SilverStone has a "recommended"list of PCIe drives, currently displaying the Samsung XP951 and Plextor M6e, among two others.
In any case, the SilverStone ECM20 supports M.2 drives of up to 80mm long, and there’s a low-profile bracket included in box for use in slimline PC systems. Given the card itself has no real logic (e.g. Controller chips) onboard, I’m not expecting the ECM20 to be very costly (maybe $30 USD tops) whenever it rolls onto store shelves.
