fan not spining as fast? bearings could be wearing out, although they shouldnt for a long time...hmm i aint sure, yeah i aint never gona get rid of the noise in my computer case, as its got holes all over it, i wonder if i use my old on whether it would be quieter? probably but i dont like that one, this new one kicks ass, cant wait to see temps on an average day, they should be in 20's for cpu temps and around 30*C for system, NB might drop a couple of degrees as i rethought out the placement of fans...
i have one that sucks air in so its blown over nb, the cpu fan also sucks this air over the heatsink which is then blown out top into PSU and sucked out through another 120mm fan, then any remaining air that is at the top gets sucked out through an exhaust fan on top, (air can enter all over though as its covered in holes)