How Does The 'Reduced' CPU Setting Work?

Hi,
I run my 1.67GHz PowerBook with the Processor Performance set to 'Reduced' most of the time to save battery life and also to keep it cooler. Does anyone know the theory behind this setting? Obviously it's reducing the performance of the processor somehow, but what is it sacrificing in order to do this?

Tim.

 

So, it's a few months later and I still haven't been able to find any solid information on this.

We've been studying the basics of OS X at polytech (which is terribly frustrating as I've been using it every day since X came out) and, while discussing the Energy Saver control panel, the concept of the 'Reduced' processor performance setting came up.

We came to the conclusion that, on this 1.67GHz PowerBook for example, the amount of computations that are performed in a second are so great that the computer is capable of 'resting' during periods of low-level operation. So, let's assume that it takes me 50 milliseconds between key presses while typing, the computer could 'rest' during those 50 milliseconds - it may seem like a very tiny increment of time, but 50 milliseconds is equal to 83.5 MHz (... I think?).

However, this kind of behavior seems to me to be more like that of an Automatic power saving mode.

I personally don't believe in this theory. I think the idea that 'Reduced' processor performance simply reduces the clock speed is far more credible - I know that I get more beachballs when I'm on 'Reduced' than I would if I were on 'Highest' processor performance.

I had a flick through a datasheet for the 7447a but couldn't find any reference to this CPU's power saving characteristics.

So, does anyone have a more concrete answer to my question? I wish I could just drop it, but I switch between 'Highest' and 'Reduced' so often that I can't help but wonder what I'm actually doing!

Tim.

 

Thanks Mitthrawnuruodo.

I've been doing more Google-ing and it seems that no one has any technical information on the different states of processor performance. I guess it's just something that people don't think about, but I would imagine that if I knew the specifics of how each mode worked I'd be able to use them more effectively.

From what I can tell, it's different for each system (I don't think my old G3 even has the option to run on 'Reduced' processor performance), so now I'm looking for information specific for the processor in my PowerBook... from memory, the PowerBook sports a Freescale (Motorola) PowerPC 7447a, right?

Tim.