CPU Governor
Trying to set scaling governor to powersave is a nice way to save some power when running Proxmox. Run the following command. Governor state will persist after you rebooted so no need to rerun it after a reboot.
apt install cpufrequtils
echo 'GOVERNOR="powersave"' | sudo tee /etc/default/cpufrequtils
Double check if your governor is successfully set by running.
sudo cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
You can run powertop to check power consumption of your CPU.
If you are running intel you can checkout how CPU governor and pstate work here: https://www.kernel.org/doc/html/latest/admin-guide/pm/intel_pstate.html#energy-vs-performance-hints
Check motherboard settings
Some motherboard manufacturers will enable multi-core enhancement(MCE) as default. Make sure it’s turned off. Also disable any extra function you are not using on the motherboard, for example any STAT port you are not using, I saved 10w of power by just disabling unused pcie and STAT ports.
Disable Intel turbo boost
If you are running intel CPU and don’t require a lot of power to run your application, you can even disable turbo boost for extra bits of power saving.
echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo
This will disable turbo boost for your CPU. Reenable it by running
echo 0 > /sys/devices/system/cpu/intel_pstate/no_turbo