I've replaced the bad Asrock x370 Taichi with a Crosshair Hero VI. My question is about the 8-pin and 4-pin 12v plugs on the top of the board. Am I supposed to use just the 8-pin or both the 4-pin and 8-pin. I'm using a Corsair HX-850i PSU and it doesn't seem to have a 4-pin connector. Any suggestions would be greatly appreciated.