This is definately not a good thing to be dealing with at 6:30 in the morning!

I turned my PC on this moring to get frighterned by this crazy ratchet like noise coming from inside my PC and its quite loud!
So I paniced and tried to hit all the buttons to turn it off, but i was still asleep really and it loaded fine, no errors at all, except for this noise!
So i shut it down and opened the case and there was nothing a miss. No fans fallen off and trying to chew up wires! (its happened to me before with a different case!), nothing out of the ordinary.
I turned it on and had a listen to the fans and it doesnt seem to be coming from them, its comign from my main board or processor fan.
At first i thought it might be because it was cold of the ball bearings n the fans, something simple

but i dont think so!
Any ideas what i can do to test this? I'm right in the middle of all my c/w and stuff, i dont think i could concentrate with that noise in the background!
I have to go to college now and sort this out when i get back, but any ideas would be very gratly appreciated!!!!