I used silent fans in mine and honestly, the loudest thing in it is the GPU fan by a wide margin, with either my older 460GTX or my new 580GTX. Second place goes to the PSU fan, which has to be bought as a "silent" supply unless you wanna do some interesting mods. Only thing louder than the NVidia cards is the ATI 9800 in Mom's machine; that thing turns into a small turbine engine in certain conditions.