I have had my Lian-Li case now for about 5 years. Just today, the rear outtake fan of the case started increasing then decreasing in speed. This is the case even if I have my case side cover off. I originally thought that it might be temperature-related, but that can't be the case with the case side off as well. Do you think the fan needs to be replaced? Why does the fan speed change erratically? Is there anything I can do? If the fan needs to be replaced, any instructions would be helpful as well. Please help!