This one is a doozy, cold boot issue

Hi guys,

I am posting here in hope of help in solving this weird problem. First, let me start by saying that I am not a noob and I actually study Computer Engineering, but this problem has stumped me.

If the power cable is ever unplugged from the PSU, the next time it is plugged in, the PC will refuse to start up when the power button is pressed. If you press the power button 2 or 3 more times then the computer will automatically boot after 3 minutes. That's 3 minutes for the power LED to light up and the POST beep to be heard.

This problem will not happen if the power cable was NOT unplugged after the last shutdown.

Another related problem is that if the computer is on and someone sets it to sleep, then it will not wake properly. The fans wake up, power light becomes solid, but no display is seen on the screen.

OS: Vista 64bit
MB: Asus P5B Deluxe
CPU: C2D (can't remmember the model)
vid card: ATi 4870

Thanks,
 
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