PC fucked

When I try to start up my PC, 6he CPU does not beep once like usual, and my monitor doesn't get any signal. It happened all of a sudden overnight while I was downloading. Any ideas on what this could be?

>>4
I already checked for that. What worries me is that I don't hear the usual "HDD-sounds" and that the CPU does not beep... Maybe the mainboard overheated? Goddamn why do computers break...