Hey looking for some help. I have a saber tooth 990fx was working fine for 3-4 months after build. Now the light on a says no bootable devices. If I reset it a lot I get no bootmgr found if I keep doing it might get lucky and turns on works fine for hour then shuts off with same error tried two different drives. Tried to boot from disk reads nothing's. Only thing been done is last week updated gpu drivers. Not sure what to try.
If you have two "bootable" drives and both are having trouble, try replacing the sata data cable.
Do you have any problem booting to a bootable DVD. You could download memtest86 ISO and make a bootable CD (may need to do on a 2nd computer). Boot to the CD (side benifit - Let run for 4 hours to check memory for errors.), If this also gives you problems, suspect the MB.