Hey
I have kind of same problem with my GA-X58A-UD3R. It worked fine for 3-4 days straight without any problems (did not turn it off).
But after turning it off one day for 8-9 hours it does not get past the POST screen, and some times i can't even see that. So can't even get in to BIOS.
I thought it was my other memory (Corsair Dominator GT DDR3 2133MHz 4GB, that i could not boot with if it got over 1600Mhz. ran it on 1066Mhz) that was not on either Gigabyte or Corsairs list of working memmory, and i had som cold boot problems with it. Got BSOD 4-5 times when i started up when it was cold, and then all problems just dissapeard and working 3-4 days straight. so i bought new RAM. I know my new ram is't on Gigabytes list either, but it is on Corsairs list.
Have tried a lot of things to now:
-Resett BIOS
-Change memory (as told)
-Check CPU pins and conectors. all looks fine
-Tried to use PCI-x16_2 for my grafic card
-Tried other grafic card
-Tried a difrent PSU
-Striped it down on a workbench to eliminate shortcuts.
The only thing i had not tried that i can think of is to try a other CPU, but can't get my hand on one.
It's frustrating to have a new computer that i can't use. just unending cycle of restarts :-(
Have any more ideas i can try?
PS: The BIOS version i used was FC, and the MB is Rev2
Best regards
Knut Vegard
Moderator EDIT: I have changed the model number of your motherboard as you had it wrong