Gigabyte recently released a UEFI BIOS (which is awesome, by the way) for my GA-Z68A-D3H-B3 motherboard and so far it's been working really well. However, I noticed that Windows was having some problems starting my dedicated graphics card after the BIOS flash; the i5's integrated HD 3000 graphics work fine, but my nVidia card said "This device could not start" in the device monitor and its display output was dead.

After reinstalling Windows 7 64-bit in EFI mode, things were running a bit more smoothly as the device was now properly detected but missing drivers. After installing the HD 3000 and GeForce drivers, I rebooted and immediately got a BSOD: IRQL_NOT_LESS_OR_EQUAL.

For those in the same situation, fortunately it can be solved very easily: don't install drivers right away. Instead, perform Windows Update repeatedly until you have SP1 installed. SP1 seems to resolve the device driver conflict that occurs and then both the integrated and dedicated GPU drivers can be loaded simultaneously.

Reference: http://communities.intel.com/thread/20515