I read on PC, how can I save power and make PC last longer by under powering the PC ?
On Windows I put max CPU state to 1%, PCIe and WIreless Power to power saving mode.
Also related question, How to disallow software from inhibiting power management?
None of the other comments here are properly answering your question, so I will pitch in.
There are two layers to this.
One layer is to use one of the many power management daemons available to you. If you’re using KDE plasma, this is power-profiles-deamon by default, and it takes care of this. Gnome has its own thing. If you want something independent, you can use TLP. You shouldn’t generally use more than one at a time. Another popular option is cpupower.
What these do is tell your CPU lower its clock speed (which means your CPU will draw less power).
If you also have a dedicated GPU (for eg. Nvidia), you should make sure that it is also powered down when not in use.
So far, you’re only communicating your preferences to the CPU and the GPU. There are however, other parts of your machine that consume power, eg, your monitor, Bluetooth and wifi modules etc. To control this layer, you need something like powertop. Powertop has an auto tune feature which enforces automatic time outs for hardware modules and make sure they go to sleep.
sudo powertop --auto-tune
But once you run this, you may find that your Bluetooth mouse may go to sleep in 5 seconds of inactivity instead of a more desirable 30, so you’ll need to go back and disable specific optimizations within power top.
There are also other obvious things you can do, such as turning down monitor brightness and disabling keyboard backlight. Monitor brightness in particular is a huge power sink.
In any case, https://wiki.archlinux.org/title/Power_management is your go-to source of information. There is a lot of outdated and misinformed opinions about this on the internet, particularly about Linux computers, because battery life is something that can easily be influenced by placebo.
I’ll also say that in rare cases, certain acpi kernel parameters can also help your battery life depending on your mobo, but this takes lots of experimentation to find out.
You can read live power consumption by catting out /sys/class/power/BAT0/one_of_the_files_here when not plugged in. Once you get your idle down to under 10 watts, that’s probably good enough.