Why do my PC fans keep revving up?
Christopher Davis
Updated on May 21, 2026
CPU's, GPU's and your motherboard have temperature sensors that are used by the fan controller to decide what speed to operate the fan at. A bad temperature sensor could lead to the fan controller erroneously thinking that the CPU is overheating, leading to constant revving of the fan.
Why does my PC fan speed up?
A CPU fan runs at full speed whenever the temperature of CPU increases. The processor generally uses a sensor that controls the fan speed. If the CPU fan runs at full speed all the time, there might be something wrong either with the processor or the sensor (in the fan).Why does my computer sound like it's revving up?
It sounds like the lubricant has dried out in the cooling fan bearing. If you're up to dismantling the laptop, you can usually buy the correct replacement fan assembly online. If you don't feel like tackling a repair yourself, take it in for repair.Why do my PC fans keep speeding up and slowing down?
Check the heat sink also on the CPU. If dust has accumulated in the heat sink finials then blow it out with a can of clean air. Try running the machine with the cover off to see if the extra air flow cures the problem. Your PC may be overheating causing the fan(s) to speed up to cool thing down.How loud should PC fans be?
A 30db low frequency noise might be tolerable, but if it is higher frequency it might be annoying. List the case and any other cooling components you have.How To Adjust PC Fan RPM
How do I fix my CPU fan noise?
How to fix a loud computer fan
- Clean the fan.
- Move your computer's position to prevent obstructions and increase airflow.
- Use fan control software.
- Use the Task Manager or Force Quit tool to close any unnecessary programs.
- Replace the computer's fans.