- slow down fan speed to reduce the noise
sudo nano /boot/firmware/config.txt
add:
dtparam=fan_temp0=60000
dtparam=fan_temp0_hyst=5000
- If it did not work then it could be bearings worn out
sudo nano /boot/firmware/config.txt
add:
dtparam=fan_temp0=60000
dtparam=fan_temp0_hyst=5000