Title says it. I've tried both cards individually, and they work fine. They also work in Crossfire at lower resolutions, but not at 1920x1080. I get a blank red screen, then a system reboot on any game. Tried both the previous Catalyst drivers and the ones released today, 13.11 Beta 8. Only thing I can think, is both cards require an 8 pin and a 6 pin. The cables coming with the PSU have 2 6+2 pins on one cable, and I used one of those for each card. Should I try using 4 separate cables?