Basically here's my situation: I bought a Gigabyte 7770 GPU, replaced my old 5770 and discovered that when the screens are set to go off the computer now freezes. I'm running the 12.2 drivers, mobo at this stage was a Gigabyte 790FX with a Phenom 9600 and 4GB of Corsair RAM. To note, it had no trouble turning the screens off with the 5770.
As I intended to run these in crossfire I bought a second Gigabyte 7770. I then tested that on its own and found the PC also froze when screens turned off. So I upgraded to the F2 bios and still had the problem. Same issue when the second card was upgrade. The mobo bios and drivers were also fully updated.
My next phase was to upgrade the rest of my computer this week once stock of FX-6200's were available. So I now have a Gigabyte 990FX mobo, 16GB of Mushkin RAM and the new CPU. I performed a clean install of Windows 7, updated to the F4 mobo bios and latest drivers etc. To my surprise it still freezes if the screens are set to go off... Is this a 7770 issue, specific to Gigabyte 7770's or even the batch both my cards came from? Any ideas would be gratefully received. Also my PSU is an Antec CP 1000w and the PC is completely stable under stress testing etc, with freezing/crashing only occurring when the screens are set to go off.