Version: 2.16 || Release Date: 2009-11-17 || License: Shareware ($10) App Owner: goulven

CoolBook is a tool for the MacBook and MacBook Pro computers. It lets you monitor the frequency, voltage and temperature of the CoreDuo / Core2Duo CPU.

Registered users can also change the frequency and voltage of the processor. Download CoolBook to find out more.

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6 Opinions

SIGNIFICANTLY increases my battery life
By default, my MBP uses 1.0 V at its min frequency (1.6 GHz), and 1.1625 V at its max frequency (2.5 GHz)

Here's how u set up coolbook:
The MINIMUM VOLTAGE my MBP can run at is 0.9375 V. I want to see how fast I can run my MBP at that low voltage. The answer is 2.2 GHz.

Next I look at the MAX FREQUENCY, and see how little power I can give the MBP and have it still work. The answer to that is a 0.9875 V at the max 2.5 GHz.
And then for good measure, I threw in one value in the middle. So here's my settings:

2261 MHz at 0.9375 V
2394 MHz at 0.9625 V
2527 MHz at 0.9875 V

I earlier said that by default, the lowest voltage my MBP will run at (when at it's MIN frequency of 1.6 GHz) is 1 V. But with Coolbook, even when running at my MAX frequency of 2.5 GHz, I'm only using 0.9875 V. So cookbook lets me run my MBP at it's MAX SPEED and still draw LESS POWER than I would if I were to let it IDLE with the default settings.

An excellent app to increase my Macbook's battery life and reduce it's heat. Great work!

From the manual (in the dmg):

- Can I damage my CPU if I run it at a lower voltage?
- No.

Known issues

No long-term testing has been performed on OS X 10.5 (Leopard).

The CPU of the "Santa Rosa" / LED MacBook Pro can be read and controlled using CoolBook, and the maximum power consumption may be reduced.
There is however an issue, making this model consume more power running in idle battery mode with CoolBook activated.
CoolBook is therefore not recommended for usage with this model.

yes this app does work, undervolting is a well known concept on the windows/linux side of town, unfortunately this app is terrible. I say this as someone who registered, coolbook is ridiculously limited.

My main gripe is that using while using coolbook you are locked into the multiplier that you have modified. Coolbook prevents the CPU from ramping up when needed.

My second gripe is that it does not work with core 2 duo imacs although the hardware is capable.

pps macman (above) is the author of the program

The best way to get your MacBook to run cooler. The fan noise is no more.

Wow, it acually works as advertised, although I don' quite understand how the adapter/battery pref pane toggle works, really good results though, with two instances of yes > /dev/null going peak temp is 69 degrees at 1.67GHZ (I have a 2 GHZ core duo macbook pro) when undervolted to 0.95 compared to default of around 74 degrees at a voltage of 1.1625. Main selling point for me is increased battery life, I get 2 hours when maxing the CPU now!, idle battery life is unaffected though, still around 4 hours.