Loud hum noise

[CraKaJaX]

Just recently I took my computer over to a friends dorm and everything worked fine. I got back to mine and hooked it all up and now there's a LOUD humming noise coming from the Heatsink/CPU area. I have no idea what it is, It's a 3500+ @ stock with the stock heatsink. What would cause this noise? It's a constant hum, and very loud.

 

[theMan]

make sure nothing is hitting the fan or anything.

 

[Unkno]

yea, it's most likely caused from something hitting the fan

 

[Fresh Daemon]

Might also be loose at one corner and vibrating against the heatsink. Make sure everything is tight. Most likely it came a bit loose, or a cable has fallen into the fan blades.