I found one similar question on superuser.com but it doesn't answer for my problem.
Today I noticed that my graphics fan doesn't spin at all. It's Radeon HD3870. I found some 'adivce' on the Internet like- buy new fan or graphic card. Instead of that I want to know if there is an easy way (to do at home) to check what cause the problem- is it only fan or power cables or something else? I will be grateful for any advices!
EDIT: After your advices I changed fan. Now it only twitch on PC start. You can see it on YT: http://www.youtube.com/watch?v=hQb-gSHZk3A Please, hear sounds of PC to, does it sound like it starts to times?