View Full Version : MacBook CPU speed setting

06-15-2007, 06:12 PM
I've been looking around on the web without much luck on how to configure my CPU speed on my macbook. I just switched from my old iBook G4, where I remember I could just go to the Energy Saver preference pane - go to options - and under all the checklist options (restart automatically...show battery status...etc etc) there's the option to set the speed to reduced, highest or automatic.

Now I go to the preference pane on my MacBook and I see that there's no option for this....?!

Where can I find this option?? There must be a way to lower the cpu speed especially with the core 2 duo chips!

06-15-2007, 06:26 PM
In Energy Saver, look under the Optimization dropdowns. Pick the better performance one to run the CPU at max, better energy savings to ramp it down.

06-16-2007, 05:52 AM
Ok, so I see that this would change sleep and display times but do you know for sure that it adjusts the cpu speed too??

06-16-2007, 09:44 AM
"For sure"? Well, no. Those better performance/better energy options are relative rather than absolute indicators of what you want to happen under the hood. In general, the better performance setting will use more of the CPU's power. There are conditions, however, under which CPU performance will be lower than maximum no matter what you set. For instance, when you're running off the battery, the SMC firmware can get involved and shift down processor cycling (or so I've read) when the firmware deems it wise to do so. The CPU also has complex rules that determine how it will function as conditions change

If you want to interact directly with the CPU--and probably void your warranty and perhaps damage your MB--you could try CoolBench, http://www.coolbook.se/CoolBook.html. Before you do, you may want to read the review here:


and the interesting forum thread (cited in the above) on ArsTechnica.

If you're the sort who wants to think deeply about what changing voltages might do, see Intel's spec sheet for the CPU: