When i press the power button on my PC it really powers on for about a half a second. I can see the fans starting moving, some leds lighting, but afterwards it goes dead. It usually takes a few tries for the computer to really start, after which is works just fine. Any idea what it could be? I have a 350 W ATX PSU, nVidia nForce2 mother board, AMD Sempron 2600+ processor. (yes it's an older computer which i'm trying to revive). Thank you for your time.