I have a quad core CPU (Phenom II 945), because sometimes I need performance, but most of the time, 4×800 MHz (the minimal frequency) is still overkill for most usages.
So, three questions regarding CPU manipulation under Linux. I'd like to know for each
A) how much of effectively reduced energy consumption is possible
B) if allows stable working
C) if it's not damaging my processor.
Linux allows to shutdown cores at runtime. However, I read somewhere that disabled cores don't actually use less energy, but as if run at full frequency. Cant find that link again, nor know if this is correct or if this still applies for my CPU. Where can I find that kind of information? Has anybody tested that? Is there an easy way to measure actual energy consumption of the whole CPU and/or single cores? Related but unanswered question: Dynamically disabling cores in a power-efficient way?
could be set to values lower than the official spec. How can I find the lowest possible value that fit a,b,c? Anybody has experiences with that?
That's rather BIOS than Linux, but I read that you can undervolt some CPUs while keeping frequency.