I ran into a simular issue, where my GA-Z68X-UD3H-B3(rev. 1.3) worked great for 2 months and then developed a boot loop issue. Turned out to be the intel display driver supplied by Gigabyte. Do NOT select the "install all" option on the drivers disk. After the Windows install, check the device manager and only install drivers for devices marked with yellow. Also, if you are using the onboard video ports, be sure and disable the pci video options in the bios settings. As for why my problem waited 2 months to surface, I don't have a clue; unless maybe it was triggered by a Windows automatic update?? I thought those were turned off but....