CoolBook adjusts Core Duo voltage and frequency

CoolBook adjusts Core Duo voltage and frequency

Summary: Hot on the heels of my story yesterday about undervolting your Core Duo CPU to save on battery and heat comes a nifty piece of shareware. CoolBook is a GUI to control CPU clock speed and voltage. It's like the author was reading my mind!

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TOPICS: Apple
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CoolBook-controllerHot on the heels of my story yesterday about undervolting your Core Duo CPU to save on battery and heat comes a nifty piece of shareware. CoolBook is a GUI to control CPU clock speed and voltage. It's like the author was reading my mind!

CoolBook is a $10 shareware application for the MacBook and MBP that allows you to adjust the frequency (clock speed) and voltage of Intel Core Duo and Core 2 Duo CPUs.

According to the author's published benchmarks his MacBook (1.83GHz) temperature decreased by as much as 14°C (25.2°F) just by dropping the voltage from 1.2125 V (Apple default) to 0.95 V (the minimum).

Other programs I've convered here before allow you manually control the MacBook and MBP's fan speed which can greatly reduce operating temperatures.

In my experience Core 2 Duo MacBook Pros can run as much as 40°F cooler than Core Duo machines. I don't consider these voltage/frequency/fan tweaking applications necessary on newer C2D machines, but they're practically required for Core Duos. Especially if you want to use your machine on your lap.

As I mentioned yesterday, there is almost no downside to lowering processor voltage other than constant crashing. If your MacBook starts getting crashy, it's easy enough to crank the voltage back up a tad until it's stable again.

Although I still hope that Apple will include fan and temperature threshold control in a future version of the OS, you can rest assured that they'll never allow us to adjust the voltage. But that's what shareware developers are for.

Topic: Apple

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10 comments
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  • Cool Math

    It seems some Math must be recalculated...

    "temperature decreased by as much as 14?C (57.2?F)"

    A 14?C temperature change is 25.2?F, not 57.2.
    brotherStefan
    • RE: Cool Math

      Hate to burst your bubble, brotherStefan...

      14?C is indeed 57.2?F. Confirmed via Dashboard converter, the National Weather Service's webpage (for Buffalo, NY) and Wikipedia (?F = (?C ? 1.8) + 32)
      ptkdude
      • bad math (was cool math)

        Talk about bursting a bubble. This is yet another example of the
        poor state of science education in the United States. If something
        cools by 14 ?C, that is a [i]change[/i] in temperature, not an
        absolute reading. Since 1 ?C is 1.8 ?F, that means that the
        reduction in temperature is 1.8*14 or 25.2 ?F.
        glgray
    • Math updated

      I corrected the story to be 25.2 degrees F.

      - Jason
      Jason D. O'Grady
  • bad idea

    Electronics engineers (good ones anyway) design things worst case.
    This is why this even works at all. But it is a very bad idea. Why do
    you want to risk crashes to get a few degrees cooler? Very bad
    idea.
    Nate Goldshlag
    • True if...

      This is true if you get the worst chip from the line. All CPUs are different.
      macpro
    • Describe the Badness of voltage adjustment, please.

      I'm new to this area of computers. I'm a programmer. But what
      does happen when this voltage is dropped? Why is it such a bad
      idea?

      Thanks,

      Curious Programmer
      StackFrame
      • It is actually only positive effects of this.

        If you run your cpu at higher voltages you will shorten the life span of your computer. And if you run it at a lower voltage it will get a longer life.

        Silicon degradiation is slower with lower energy.

        Your cpu fan will get a longer life.

        The battery aging slows with lower temperatures.

        So undervolting is actually only good for your computer.
        macpro
        • until it crashes intermittently

          Silicon runs slower at lower voltages. You are pushing designs that
          were done worst case at a certain frequency closer and closer to
          failing. And worse - they could fail intermittently.

          This is a **very bad** idea. Go with the way the engineers
          designed it.
          Nate Goldshlag
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