@digitalwanderer
http://www.overclock.net/t/1551060/official-samsung-sm951-owners-club/1120#post_24873865
Making your SM951 NVMe SSD bootable on Gigabyte GA-990FX-GAMING motherboard.
Turns out, it's not that hard but if you're using Windows 7 or older, you're in a much more difficult predicament because Win7 doesn't have an NVMe driver on the installation disk / ISO / USB stick etc.
THIS method should work using Windows8 or higher.
You'll have to do a fresh install because the partitions that you have on your root drive where your current O/S is installed are probably MBR and you need to use GPT on the Samsung SM951 NVMe. At least that's as much as I understand about the whole affair.
So FIRST of all: Don't physically install the SM951 just yet. If you do and boot into Windows, Windows will automatically partition the drive using MBR or something wrong. No big deal this can be fixed during the fresh install process.
1. Get Microsoft's "MediaCreationTool"
2. Plug a USB 3.0 flash stick into a USB 3.0 port on the back of your PC. [6GB or greater will suffice.]
3. Choose "Create Installation Media for another PC" and wait for the app to finish creating your WinX installation thumb-drive.
4. Shutdown your PC, unplug it and open the case.
5. Disconnect all drives from all your SATA ports.
If you have a grounding wrist-strap, you should put that on now and attach it to the chassis.
6. If your GPU or other card is located in SLOT 1, it is highly advisable to remove it, so you'll have unhindered access to the M.2 socket.
7. Remove only the top screw from the 80mm hold-down located inline with the M.2 socket toward the rear panel.
8. Look into the M.2 socket and note how it is keyed. Look at the SM951 and note the notch in the card-edge contacts.
8. Hold the SM951 by the edges at about the middle area of the card with the IC components facing up. BE GENTLE! and slide it into the M.2 socket at a slight angle.
9. Push the rear end of the SM951 downward to the anchor point. Should require very little force.
10. Install the hold-down screw.
11. Reinstall whatever expansion cards you removed for easy access.
12. Is everything disconnected from your SATA ports? If not, make it so.
13. Plug your PC back in, press the POWER button and then press DEL to enter BIOS.
14. Set all BOOT options to "UEFI ONLY" where possible. Also check to see that the motherboard is recognizing the Samsung SM951 by selecting the "Peripherals" tab and scrolling the bottom-most item and hitting ENTER.
15. Save settings and EXIT
16. After BIOS POST you should enter boot off the USB Thumb Drive and see the Language Selection screen for Windows Setup.
17. If you created the installation media using the Free Upgrade version of Windows 10, just choose to SKIP entry of the "Product Key" code. You'll be asked twice and choose SKIP both times.
18. Windows Setup will allow you to choose which drive to install on. Make sure to select the Samsung SM951.
19. If you already installed the SM951 earlier and booted into Windows, there will be existing partitions on the drive which you will need to delete. Delete all partitions until you see a single partition of "Unallocated Space". Now click on "NEW" and SETUP will create new partitions for the install.
20. Continue with setup until Windows restarts. Each time Windows restarts, you'll need to press F12 during BIOS POST and select "Windows Boot Manager" as the boot device, otherwise you'll boot into the USB flash-drive and start the SETUP all over again.
21. Remove the Installation Thumb-drive.
22. Once Windows 8/8.1/10 is fully installed, you can shut down your PC and reconnect all your SATA drives into the SATA ports but DON"T use SATA port 5 which is the one at the bottom right side.
NOTE: You CAN have SATA ports 4/5 set to "IDE" in the BIOS to support older optical disk drives and plug said drive into port 4. (at least this is working for me).
So that's it. This post probably needs improvement. I'll come back to it later.