I keep mine on 24/7 but switch off the monitor and speakers when I go to bed. The screen saver kicks in after 10 minutes when I'm not in or at the PC.
I leave it on 24/7 because I have a webserver running on it and also can't be bothered with the process of switching on and off as it takes too 'effing long (god 4/5 minutes from switching on to getting to the desktop)
Those pictures on the other forum are truly shocking!
Makes me a little bit worried now of leaving anything on ...
Anyone good with electronics and the like know what could have happened with it? Also, was it overclocked?