Originally Posted by Laurijan
Ok i tested with another GPU a XFX 6950 and i have the same problem - now i am sure its the mobo.
What makes you sure that it is the motherboard? The motherboard doesn't do much to the PCI-E. I would reseat your processor because that is where the PCI-E lanes go. It's also where DMI goes. It's also where DRAM goes. Did you fully uninstall your drivers after swapping the cards or did you let CCC figure it out on its own? If PCI-E was at fault, I don't think your video card would work at all.