It's nice to finally start seeing more motherboards with M.2/NGFF slots on the motherboard. So far most of the offerings have only one slot, and still sport way more SATA connectors than anyone needs. But I expect the offerings to get better through 2017.
Another thing to note is that there is a new 2.5" drive form factor... same dimensions as a 2.5" SATA drive, but with a different connector, which allows more substantial 2.5" form factor SSDs to use NVMe. There is also a new on-motherboard connector standard for the new 2.5" drive interfacing that makes use of a blocky SAS connector (but is not SAS... is PCIe for NVMe interconnect), and there are motherboards available now with one of these on them. And, again, in 2017 I fully expect motherboards to start coming out with more of these connectors.
In the mean time you can get standard PCIe cards that farm-out the correct connector for what you need (either the NGFF connector or the SAS connector). Please note that BIOSes for motherboards without native connectors probably do NOT support booting from NVMe, and if they do it will be UEFI booting only (no legacy booting from NVMe).
Just by way of information: M.2/NGFF is basically just a PCIe bus in a different format. It's a compact 4-lane PCIe bus format. However, there are *FOUR* different connector styles for M.2-style connectors, called by various names (M.2, NGFF, mSATA, mWIFI, and other crap). Be very careful to buy stuff that matches up. You want the NGFF connector (also known as M.2, but NGFF is the modern term for it and will be less confusing). This connector has one notch to one side and one hold-down screw at the end of the board along the center-line.
Another thing to be careful of is that a bunch of vendors have NGFF boards that are *NOT* NVMe. The boards actually have a SATA controller on-board and will attach via AHCI. Examples include Kingston HyperX and Plextor. All the Samsung products are NVMe.
For low-cost NVMe, another alternative to the 950 Pro is the somewhat older Samsung NVME SM951.
Most of these NGFF NVMe boards are capable of doing 3 GBytes/sec reading (deep queue). Writing will be a lot slower, even slower than a typical SATA SSD due to having fewer flash chips. Also, 3 GBytes/sec is if you plug it into a PCIe-v3 slot. Most machines out there today will have PCIe-v2 slots and performance will be more in the 1.5 GBytes/sec range. It is still fast as hell reading.