Your laptop, just like your car, can start to overheat when it's working or "thinking" really hard. The more programs you're running or the more complex your computer functions, the more your computer has to do -- and that can cause its central processing unit (CPU) to heat up. At that point, the fan turns on to cool down your laptop. If your laptop fan is constantly revving, you might need to upgrade your computer's CPU or get your fan cleaned to better handle the workload. Don't ignore this problem because it could result in a potential computer meltdown.