rma mobo or proc?

Ok, well for the lan party tonight i was going to have a rig ready for my cousin to use, so the parts come in. Long story short, the PSU I received was burnt up, so I have to rma it, the ram, video card, and hdd all work fine. I cant test the mobo or processor though (since I cant get the hsf off my rig). The rig turns on, but their are no beeps and it doesnt post. So which is likely the cause?