How to measure power consumption on a non-laptop system

[Alan Jenkins]

Peter Hüwe wrote:
> Hi,
>
> is there an easy way to figure out the power consumption of my machine, which 
> is a normal desktop pc ?
>   
No.

There are power meters you could plug your computer into, which is 
probably about as easy as it gets.

CPU's with frequency scaling advertise claimed power usage in 
/proc/acpi/processor/CPU0/performance.

I don't think there's an equivalent for any other component, though if 
you could see if other people have measured power savings with 
components which match yours.  E.g. if you're considering the ATA Link 
Power Management patches, someone may have measured and published power 
savings for ATA hardware similar to your own.


If you have a good CPU temperature sensor and disable "smart fan 
control" (BIOS option), you can use the CPUs temperature as an 
approximate, relative, non-linear measure of its power usage during 
experiments.

e.g. I use highly inadvisable kernel patches to undervolt my CPU, 
lowering the voltage used at maximum frequency to the default used 
during the minimum frequency.  I'm not suggesting you try undervolting, 
but I compared the temperatures with the CPU under load, and I did see a 
difference.  You should see something similar with enabling CPU 
frequency scaling.

Alan