Many people in the voice over industry complain about the loudness of computers and hard drive fans. You're trying to create the quietest environment possible, and here your computer's fan sounds like a leaf blower on steroids. Most people, such as myself, keep their computer outside the booth, so the fan sound isn't really an issue. Nevertheless, on my last setup I still installed a custom low-noise fan just to help keep the db down. Some people record with their computer or hard drive in the booth with them, but then they need to make sure they're using a fanless computer and/or a SSD.
I've heard of "extreme PC cooling" before - submerging computers in oil (yes, I'm serious), running ice cold water tubes all over them, etc...but this one made my jaw drop, the creator claims it's "0 db," it uses water cooled tubes, and it's built with copper! Perhaps a little overkill for my needs, but I like the steampunk!
Found via: PC World, a Great 10 Picture Slideshow