So when you installed windows 10 did you unplug all other devices like sata 3 n 6 drives? Did you use a usb stick to load win 10 or a cdrom? I'm amazed how it found that device as bootable. Do you see the 950 in your storage device section of your bios and what is it named under bootable...
I have a x58 rampage 3 black edition and even with the riser card don't you need a UEFI bios to recognize the drive so the system can boot from it?
Did you flash your bios with a UEFI Mod version for your MB? You're actually the first person I've bumped into on the internet that can boot from...