Cheapest DIY PC Sound Dampening
Well, you can go out and look for sound dampening material, or order them online.
OR you can just grab a towel and do it yourself. For really cheap. You may not even have to buy anything. And it takes very little time. Just use a little creativity and wallah.
Music:
Twin Shine - Silent Partner
Heavy - Huma Huma
Hamster Dance Song (overclocked)