I installed a gtx 1080 on pcie 4 and already had a gtx 960 which I put on pcie 2. (which the gtx worked fine before installing gtx 1080) It reads the gtx 960 but not the gtx 1080. I installed latest drivers. Still don't see gtx 1080 in device manager. I looked at a computer power calculator and it read that I should have enough power.
Asrock EP2C602-4L/D16 W/Dual Xeon e5-2670
Croshair cx 750m PSU
EVGA Superclock Geforce GTX 1080 W/NVIDIA GTX 960
Asrock EP2C602-4L/D16 W/Dual Xeon e5-2670
Croshair cx 750m PSU
EVGA Superclock Geforce GTX 1080 W/NVIDIA GTX 960