The fan in my laptop computer speeds up and gets louder
While working on your computer, you may notice the fan inside the computer speeding up and slowing down, often getting louder and quieter as it changes speeds. As long as the fan continues to spin and does not completely stop this is completely normal for computers, especially laptop computers.
To help keep the noise down in computers most manufacturers today have variable speed fans, which means that the fans within the computer are capable of changing their speed depending on how hot the computer is getting. Typically the fan speeds up when doing something intensive such as playing games. Each thing you do on your computer cause your processor, graphics card, and other devices in your computer to work, which causes heat. If the fan is not taking out enough of the hot air or bringing in enough cool air, the fan speed needs to be increased to help prevent any damage.
The reason you are more likely to encounter this situation with laptop computers is because of the size of the fans in them. Smaller fans do not move as much air as a bigger fan and must go faster when the computer is getting hot.
Tip: With many laptop computers cooler air comes in through the bottom of the laptop and the hot air escapes from one of the sides. If you are working on a laptop from your lap, this can constrict the airflow causing the computer to heat up. Try working on a hard flat surface instead of your lap or use a cooler pad or another device to give the laptop room to breath.