I've been getting weird patterns with my fan. First off, it's started to make a sort of purring sound every now and then, usually when it's running a bit louder than usual. The strange thing though is the way it is tied to the power supply.
I have my comp plugged in, the fan starts to run really loudly. I unplug the computer and the fan immediately dies down. One minute later, the fan gets loud again. I plug my computer in, and the fan immediately dies down. One minute later, it gets loud.
It keeps going like this. I wonder if there may be any problem with the fan.