The good new is, the fan is running! Temperature is an enemy of computer parts, and the installed fans are trying to eliminate the problem. When the fan becomes noisy, it could be there are too many processes running on your computer, or perhaps a dust buildup that is preventing cooling, or a foreign object is stuck in the fan. Sometimes an easy fix, sometimes not. In either case you should have a noise level that allows you to be productive. The cause can be determined and fixed, it is not likely a user serviceable item.