I've installed genuine Apple Radeon HD5770 card as a second card in my Mac Pro 2008 with Crossfire bridge. Everything is working well on both Mac OS X and Windows, but I when I start Catalyst Control Center and Enable Crossfire it shows me blue screen of death ??? I was using both Catalyst 11.2 stable and Catalyst 11.4 beta. Apple card is in slot 1, XFX card is in slot 2. The good thing is that the XFX card is now working in PCI Express 2.0 16x mode - 5 GT/s !!! I'm using Windows 7 Ultimate 64-bit.