Hello,
I responded to the question on Amazon and as you can see from my signature it is possible to BOOT from the Samsung M.2 Drive. As PRAZ has said above the Setting are in the UEFI and then change the drive priority and then boot order. If you are still having issues i can try to take screenshots of my BIOS settings at the weekend.
thanks
Obsidian 800D Case
Rampage Extreme 5 X99
Intel i7 5960x Extreme Edition
Corsair H100i Cooler
Corsair Dominator Platinum 16G 2800 MHz
Samsung XP941 512 GB (Boot)
2 x M500 SSD Crucial (Raid 0)
4 x WD 2TB (RAID 5)
2 x GFX 780 TI Kingpin (SLI)