If it's the exhaust fan it's not nearly as important as perhaps the HSF fan which actually takes the heat from the CPU rather than from the case.yeah, it's real important, it takes the heat away from the CPU, the fan may be shot.
It could be a thermally regulated fan also and it not being on would be normal operation if there isnt a need for itIs it possible it was unplugged or something? is that connected to the psu? cuz i just recently bought a new psu and installed it so I may have forgotten to plug it maybe??
Hehe, wasnt it also making noise? Or do you have one of them fancy quiet ones?lol i feel so stupid...from where i was sitting it looked like the fan was sitting still but its running at full speed...i put my hand behind it and i felt air lol