I use a head set when I excersize so I turned off the computer speakers and pulled the plug from the computer. I plugged the head set into the back of the computer and turned the computer on. I heard 3 beeps in the head set so it seems to be related to the computer. There is a plug marked HD AUDIO from the Corsair 900D case that would plug into the motherboard but where the motherboard guide says it should be plugged in the two plugs are not the same. The motherboard has a blank space at top right and the case has a space top second from right. Could that be it???