Recently I bought a Topton Ryzen 9 5900hx minipc which is silent under normal usage, but become very loud under load and needed some way to make it quieter.

I tried lm-sensors and fancontrol, but the fan was not detected.

I answered bellow with the solution that I found.

Someone has a better way?

How to limit the performance to reduce the fan noise [Ryzen APU / Ubuntu 23.04]

To solve the problem, I limited the frequencies of the CPU/GPU:

• CPU frequency to 30% bellow the maximum boost frequency;
• GPU performance profile to low frequency.

The performance is still good and the computer become very silent. The fan still activates, but I have to put my ear on the device to hear a faint whisper.

sudo nano /etc/rc.local

   echo "quieter operation: disabling boost"
   echo 0 > /sys/devices/system/cpu/cpufreq/boost

   echo "quieter operation: reducing CPU max frequency"
   for policy in /sys/devices/system/cpu/cpufreq/policy*; do echo 3200000 > $policy/scaling_max_freq; done

   echo "quieter operation: reducing AMD GPU max frequency"
   echo "low" > /sys/class/drm/card0/device/power_dpm_force_performance_level

It was necessary to guess the max frequency. The command to set maxfreq can be applied without reboot. Just open a terminal and execute:

sudo bash
for policy in /sys/devices/system/cpu/cpufreq/policy*; do echo 3200000 > $policy/scaling_max_freq; done