I have 7 fans on my tower desktop computer if you include the fan in my power supply, and video card cooling fans. I also have one fan to cool my hard drive.
12 fans in total in my PC. 8 of them are high static pressured fans running constantly @ 100%. (Sounds like a jet engine, but doesn't bother me much) Other ones are a bit more silent but still run at 100% to keep things cool. All fans are from Corsair.
My desktop has one large fan and while it works it gets pretty noisy if the computer is doing intensive tasks. I think it's because it is an all-in-one.