I have this motherboard and my card would only run at x8 in the 2nd slot. It should work at x16 but i couldn't get it to work even after playing with BIOS settings. In the bios you can monitor the PCIE slot / current configuration. It was giving me the warning saying that for best performance, put the PCI-e into the 1st slot. I couldn't find any reliable info about how to get it working online but I gave up as I can use the 1st slot.