My friend has a p4 desktop that doesn't boot up anymore (it really doesn't do anything).... I go to check it out and plug the PSU cable into the wall and a really high pitched, constant noise comes from the computer. The yellow LED on the front of the case comes on and a green light by the RAM lights on the motherboard. The power and reset buttons do nothing. I'm assuming that it's a bad power supply but I don't have an extra one lying around to test. Any other ideas? 