im running 2 r9 270s in crossfire and i lose performance compared to a single card, how can i check if the second slot is not x4? catalyst says both my gpus Graphics Bus Capability is PCI Express 3.0 and maximum capability is 2.0 x16 and the gb\s is 179.2 on both cards. my cpu is an oc fx 6300 to 4.3ghz