I have two Diamond 7970s that ran in Crossfire on my P55 SLI mobo with Windows 7 Pro x64. Anyone having trouble getting it to work on the Z87 FTW? Windows for some reason is not detecting the second card in the second PCIE slot (8x), after a fresh install. (it's not the power supply, I have a 900 Watt Antec Crossfire certified PSU!) I think it may be a BIOS setting, but I'm lost in there and their on no guides for understanding the settings. Help!