Like the title says, I replaced the motherboard on this computer today, it was identical to the original, sent directly from HP. So I installed it, ate some lunch, came back to test it, and it wouldn't turn on. I double-checked the power supply connector and the power switch connector. It had occurred to me that the problem may lie with the processor, but I can't check it again until tomorrow and was hoping to get some peace of mind tonight by at least having a rough idea of what might be wrong. Can anyone offer some advice?