I own a home built PC, rather old, specs are in my signature below. been running smoothly and one day I came home to find the PC dead. Last it was seen alive, my son was playing a video game and the screen went out, but the computer sounded like it was still running. I came home from work, turned it off to reboot it. When I went to start it again, I got nothing. Unplugged the PSU, plugged it back in, flipped on the computer, hit the start button on the front of the case, nothing. I have an brand new power supply (480 W) still in the box, so I took that out, switched out PSUs, and again nothing. I watched the fans in the case, and when I hit the start button the fans looked like they wanted to come on, and still nothing. Not even a weak attempt to start. I'm assuming that since I tried a brand new PSU out of the box that it's probably NOT the power supply, but where else is the problem? Is it likely the mobo, CPU? I'd like some guidance before I commit to the new mobo and quad core processor. My mobo's over three years old so i won't be RMAing it, and the processor is slightly over the three year mark.