Odd Random Shutoff problem

Okay for the last few months my PC has been randomly shutting of and refusing to start unless i put it on its side. like flat... and occasionally it just stops and creates a horrible sound in my speakers. I have no idea why this is happening but i think it might be my PSU. But honestly i need an expert on this, Please and thank you :)

Any extra parts laying around so that you can help pin down the problem?

Also, specs?