Could you fill in your system specs? Knowing the rest of your system might explain why this is happening.
4x8GB A-Data 1333MHz
Asus DirectCUII 7970
Did I miss something?
I will re-install windows, install VGA, chipset and sound drivers without installing afterburner. If the problem still exists, I will try overvolting the card a little bit (any suggestions about how much?) and if that doesn't work I am sending the whole PC (a friend of mine had a similiar problem including A-Data RAM, so it might be the memory and I don't have any other DDR3s lying around :/) to tech support.
PS: So, even with +15% power from OverDrive I have the same problems. I will be sending the PC to tech support.