I just powered on my CPU and the fan was making alot of noise like it was running on diesel I am not a technical expert on PC's and I know i have 2 fans in my CPU. The on in the power supply and the one over the CPU/ WHich one is it likely to be thats making the noise? I know how to fit a fan and they are cheap but i need to know which one. Thing is the sound goes away after about 5 minutes of uptim after boot so it makes noisr when the RPM is slow. Help plz?