Seriously sounds like your chip is getting wet... not sure though. Take everything apart and put it back together piece by piece. I had a GF2 MX that shorted out once. Water wetter is stick so the water was stuck to it, and it wouldn't boot. So (i know this is stupid but what did I have to lose
) I took off the heatsink and I washed the card w/ soapy water (to get off the water wetter stuck to it). Anyhow, to make a long story short, the thing now works. However, it doesn't o/c more than 1 - 2 mhz higher than stock speed... maybe that's what is happening to your CPU.