I put my friends 670 in my 1st pci-e slot and then after using it for like 5 minutes put my 570 back into the slot. The pc would not recognize my 570 at all in the slot no matter what we did. We put the 670 back into the slot and it recognizes it write away. We then put the 570 in the second pci-e slot (the 8x one) and then it recognized it. Was the weirdest thing ever. I put my new 970 in the first pci-e slot and it works flawlessly.