being a bit of a pleb here i can't remember how to get to the screen where you can select the speed of the processor, it's the option screen with 3 settings lowest, automatic, and highest can anyone remind me please.

 

I take it you mean for a laptop? System prefs / Energy saver.

 

ah thats it thanks

 

If you have a G5 then anything other than reduced will make your fan go loopy!
I now leave mine on reduced all the time, it still runs quick