Unplug power supply from wall. Then hold down the power button for sometime til it does not function. Then pull out the battery on your motherboard. After 5 minutes put it back in and power up your rig. See if it works. If this didn't work; mess with bios settings such as pci-e gen and "above 4g decoding". But before all this check your rig by hardware. Search for any bent pins from risers or broken wire or pci-e x1 connector(this happened to me) i would be glad if you send a picture of your motherboard.