I have a computer that I built that when I turn it on, it won't beep on POST. The power button won't turn off the computer either. I unplug the power cord and plug it back in, then it will still not post, but the power button will turn off the computer. I turn the computer back on and it posts every time after that. If I leave the computer unplugged for a while, the same cycle happens. Any suggestions? I have booted with only the motherboard connected, then one device at a time. Is it a capacitor?