I have 10 fans, most of them lower CFM to keep them quiet. I use a fan controller on the loud ones. I have one 120MM intake/one 120MM exhaust, 120MM fan over the CPU/80MM intakes on each side, 2 80MM fans on a Tweakmonster bracket over my video card, 2 60MM fans over my ram and 2 more 80 MM fans over my moffests/heatsinks on the motherboard (since I run with the 5V memory jumper on all the time).
Not loud at all, I can only hear it when I am sitting in front of it. When I am gaming, I just crank up the sound and I cannot hear anything else anyways.