CPU stepping down vs power consumption

Hey Guys,

 

I recently moved to unRaid, migrating away from Synology as I want a bit more flexibility. 

The cache drive (among other things) is implemented well on unRaid so I'm very happy until now.

 

One minor thing I'm struggling with though is the processor (and the power consumption it has).

My build has one of the new generation i3's (Intel(R) Core(TM) i3-9100 CPU @ 3.60GHz to be precise) and it works well.

I'm looking into making it more power efficient and while doing my research I stumbled upon several threads which cover the subject quite nicely like:

or

 

The newer CPU's also seem to get very high in idle utilizing the intel_pstate driver, so I'm testing the acpi_cpufreq way.

 

One thing I cannot really understand though:

While using the cpu scaling governor set to powersave:

- Using the intel_pstate driver, the CPU frequency is constantly at 4000 MHz(-ish).

- Using the acpi_cpufreq, the frequency clocks back to 800 MHz (since acpi_cpufreq set to powersave set the minimal clockspeed this seems to check out).

However, I do not get any noticeable different in power usage.

 

I would suspect that if the clock speeds drops (significantly), intel Speed Step would kick in and also lower the voltage that the CPU gets (which would lower the overall power consumption).

Now I suspect powersave on the acpi_cpufreq is probably not the best choice as ondemand lets the cpu scale op more quickly (if I may trust my sources), but since it clocks the frequency down a lot, it should let me see a drop in power usage right?

 

Hoping one of you can point me in the right direction.

I already fiddled around in the BIOS, changes various settings, making sure cpu voltage is set to auto and speed step is turned on. c state are also enabled.

 

I appreciate any help!

 

Cheers,

Sidney