I have an HD 7970 DirectCUII card which was purchased today. I've installed it into my Sabertooth X79 motherboard (which currently had an HD 6800 series card working in it) and it failed to boot in PCI-E Gen 3 mode. I ended up having to put the 6800 back in to get into the BIOS and set to PCI-E Gen 2 mode. Upon doing that the card works as expected (Using the Asus driver, the current AMD provided driver produced strange artifacts).
I'm kind of at a loss as to how to get this card working in PCI-E Gen 3 mode. I even tried setting 2 of the x16 slots to gen 2 and just one slot to gen 3 with no luck.
Thank you in advance for any support.