"Also another thing you should do is either enlarge the holes that a fan
sucks air through, or cut them out entirely. This should definitely cut down
on noise. And do consider this if you have a 92mm+ fan sucking air through
holes in the case, because the turbulence caused from the air passing
through the small holes."
FULL STORY @ GAMINGIN3D (http://gamingin3d.com/octips4.shtml)