Weird crash problem

[Badgerpoo]

Recently my computer has started crashing, but in a strange way.

The screen goes black, the power light goes off but the fans continue whizzing exactly as if it were on. Pressing the power button induces a startup as if it had been started up from cold. Nothing has changed that I know of to prompt this behavior. The computer is overclocked, but temps/voltages seem fine throughout. Its not happening under load, rather at random times.

Any idea what kind of software/hardware fault would cause this behavior?

Specs:

s939 neo4 ultra mobo
3700+ @ 2.9GHz
2x512MB generic RAM
X800 XT gfx

 

[Curiosityx]

Have you actually tried running it at stock speeds with no tweaks? Even if the temperatures are showing as normal you can still experience memory errors when running the CPU above its recommended frequency.