when I install my Rx 580 in my PCI-e 16x 3.0 slot I get no video output but when I put it in my 8x 3.0 slot it works fine. and also if I put my old GPU in the 8x slot and my Rx 580 in my 16x slot it gives an output. it works fine but I don't like that it's in an 8x slot.