I have the E machine desk top as pictured and the CPU fan is what is making the noises as you access files the the CPU fan increases in rpm's when the file is open and the load is decreases the fan slows down. One problem I have found with this that if your tower is not in a good area to receive air flow the CPU will get hot if just sitting Idle and go to a blue screen of death. just turn the computer off and let cool down and restart.