Follow these steps to determine why one or more of these fans may be making loud or strange noises:
If the noise appears to be coming from the hard drive then you can confirm this by turning off the PC, unplugging the power plug from the hard drive and restarting the PC. If the noise isn’t heard then you can be pretty sure that the hard drive is the culprit. There’s not much you can do about a noisy hard drive, often it’s a sign that the hard drive is on its way out and you should replace it immediately while you can still retrieve data from it.