With computers producing more heat then ever before people are equipping their computers with bigger heatsinks, and more powerful fans. The big negative effect is the increase in noise that comes with this extra cooling. I've made a decision to change my ways, and so gone are the days of using a 7000RPM Delta fan which screams like a vacuum. I just can't stand the noise anymore. When I recently moved my system from AMD to P4, I was amazed at how quiet my computer had become but I was still not satisfied. I was determined to quiet it down even more!
There are plenty of sound absorbing products on the market like this and this, but what I wanted to try a trick and keep things cheap. What I did to try and "quiet" down my computer was tape some antistatic Polyester foam to the inside panels of my case. Polyester (this black foam comes in most retail motherboard packages for cushioning). While Polyester foam isn't the most technically engineered sound absorbing material, it's readily available at your local computer retailer and will most likely be free!
After doing this quick little trick I found that my computer was a few decibels quieter and some occasional rattling from the side panels (I have an 3 year old Lian Li PC-70 Aluminum case) had stopped! My computer is a little bit quieter, and I think we can all agree that is a good thing. If you think your computer noise is unbearable this little mod might be worth a try.