Buuuzzzzzz

[el Chi]

For some reason I've started getting this really odd - and incredibly annoying - buzzing noise from my PC. It's not there as soon as I turn it on, it just builds up getting louder and louder. By giving it a little slap on the side, it seems to calm down but only momentarily before building up again.
Any ideas/suggestions?

 

[Asus]

It's probably a ribbon or power cable touching the fan blades a bit. I guess it could be a bad bearing in a fan too.

 

[gweedodogg69]

On my old motherboard (ASUS A8N-SLI Deluxe) the chipset fan would slowly get louder, but those boards have faulty fans anyway.