I bought an Arctic Cooling Accelero S1 VGA Cooler for the 3870. I got it on and everything seems to be running a lot cooler. When I have the card overclocked to 872/1201 games just freeze. For example, i can play call of duty 4 for about 20 minutes and then it just freezes. I have also flashed the card with the latest BIOS and i have a 750w PSU. Anyone have any ideas on why the games are freezing when overclocked?