i have strange problem with my computer. i tried to turn it on, the computer was started ok, but i didnt see anything on screen. i tried to understand what cause the problem. its was'nt the HD or the screen. when i opened the computer, i saw that the fan connected to my motherboard didnt work. the funny thing is that i drove to a friend of mine, so he would fix me the computer, and when we tried to open the computer there it worked somehow and the fan worked also. when i came back home the computer again didnt work and the fan didnt work as well. does someone know what can cause the problem?