I'm running an ASUS P5K Premium board with an overclocked Q6600. This is a total newbie question but... about an hour ago it was working fine. I had to move it to another location and took a little time to vacuum some of the dust out (plastic vacuum extention of course).
I figure I've knocked something or other, because now I get no beeps on startup and no output to screens. I get some USB activity (Razr mouse lights up blue; keyboard won't light up in various ports). I suppose the logical thing is that something's accidentally come unplugged. But what?
I don't know if this qualifies as a clue, but if you have an overclocked processor on this board, when you turn it on (from a total power off), it goes on, then off, then on again before booting. It still does this.