sometimes in games, like farcry, the game freezes, screen goes black, monitor goes off and on and off and on and off (the light on it), and then it comes bk on and farcry is working perfectly, and as far as i can tell, clock settings did not change, so what could the monitor off and on thing be?
That could be the GPU overclocked too much as when the RAM is overclocked too much the screen usually fills with lines and the computer locks up!
Try putting settings back to default and see if it happens again!