Windows Vista and CPU energy saving

kike_1974 · Post by **kike_1974** » Wed Jun 18, 2008 7:20 am

I'm new to windows vista and I don't understand how it manages cpu energy saving.

In windows xp I used crystalcpuid or rmclock to adjust voltaje and frequencies using differente P-states.

But now, in vista, I've seen that there is an option to manage cpu energy. It has only two options:
- Processor Min. State (default:5%)
- Processor Max State (default:100%)

(maybe they are not the exact names in English, I have my windows vista in Spanish)

If I change the max state to 50% for example, I see temps reduction while running orthos, and I also see reduced performance. But in CPU-Z I can see that the cpu frequency and voltages are the same, so I don't understand what vista is changing.

Any information about this?

sjoukew · Post by **sjoukew** » Wed Jun 18, 2008 11:15 am

If you use the "ballanced" setting, vista manages the cpu frequency itself, Just the EIST features from intel which do just work.
I have also seen the other options you describe, but haven't figured out how they work either.

kike_1974 · Post by **kike_1974** » Wed Jun 18, 2008 1:30 pm

What I did, just for trials, was creating a new profile. And I tried to change those values for min and max states. Frequency and voltages where constant all the time, but performance and power consumption where affected when changing options.

I guess that is some kind of "halt" instructions that vista is using to reduce consumption, but I'm just guessing.