the 3 pin from the power supply, is for the power supply fan, and usually it s just for fan speed monitoring, as long as the connectors fit, it should be the right kind, they are keyed so you can not put say a EPS12v into a ATX12v, there are only two board connectors you should worry your self over, the main wide one, and also a 4 pin one, if the board has the matching socket, if not then don't worry about it.