I have been trying for several days to figure this out and Im stumped. Hoping an ATI guru can give me some guidance. I have 2 5770's (an XFX and a Asus, both Juniper cores with identical timings) running in X-fire Crossfire. I had the XFX and just bought the Asus with the intention of x-firing crossfiring them. At first it worked fine. But now no matter what app/game I run only one core gets used. Running benchies/games confirms this. For example, my XFX averaged around 21 FPS in Unigine Heaven benchmark. When I first crossfired that went up to 47 FPS. Now, Im back down to 21. Now, Using AOD to watch my GPU core usage only 1 core is being used while running any game/app. Running MSI Kombuster one core's temp goes up in the monitoring window while the other stays steady at 32c. Now, If I watch my usage and temp using GPU-Z it shows all my core's temp rising when running Kombuster, Which is very confusing. Also, GPU-Z shows X-fired crossfire enabled, but shows one core disabled (Pics below) I have uninstalled/re-installed ATI software/drivers (Latest Catalyst suite), ran each card individually in each slot and swapped them between the primary and secondary video slots, tried different X-fire crossfire bridges, and nothing has fixed it. X-fire crossfire is enabled in CCC. Now, I "think" I was running an earlier Catalyst suite when I first installed, but I dont remember which one. That shouldnt matter though unless the latest suite has an issue with x-fire crossfire. Any ideas would be greatly appreciated.