I am running 64 bit Xubuntu Gnu/Linux on a machine based around an Intel 3930k and Intel DX79si board with an updated BIOS. My GPU is a PowerColor 7970. Everything should be capable of running on PCIe 3.0; however, I only seem to be able to detect 2.0 capability. Message board chatter is inconclusive but hints at the possibility that the SandyBridge-E processors are not capable of running PCIe 3.0. Does anyone have any additional insight?