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A simple way to prevent PowerBook fan activation System
I've just starting using the online version of Rosetta Stone's language learning software. One of the features I like is the pronunciation practice, where you listen to a phrase pronounced by a native speaker, you try to say it into a microphone, and they then display several waveforms of each sample, and rate how well your version matches the model. It's not perfect, but it works pretty well.

Until the PowerBook fan comes on, which it does every eight or nine trials! Then, even a headset microphone picks up the little "whir, whir, whir" noise, and you basically have to sit and wait until the CPU cools back down so you can continue. Very annoying. Well, I came up with a simple method that so far has eliminated the fan noise with no risk to the electonics inside the PowerBook, and it's really simple: just unplug the power cable.

The CPU speed preferences are set to slow down when running on battery power, and running slower translates into lower temperature and no fan usage. In fact, after a few days of trying this, the fan came on only once, and that was when I inadvertently plugged the power cable back in!

There are probably other situations where this won't be acceptable, where the CPU needs to run full blast, and I'm sure that there are times with the fan runs even at the lower speed. But in voice-actuated situations that require less than full CPU speed, this hint may be helpful.

[robg adds: You could do the same thing with a custom Energy Saver profile under "plugged-in," of course. But if you did, you'd then have to undo it each time you finished what you were doing. Pulling the cable sure seems like the quickest solution.]
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A simple way to prevent PowerBook fan activation
Authored by: zpjet on Nov 10, '05 09:06:17AM

i think the same trick would do selecting "Better Energy Savings" under Battery Menu Extra...

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A simple way to prevent PowerBook fan activation
Authored by: TrumpetPower! on Nov 10, '05 09:48:28AM

...or, you could use my favorite trick. Get one of those blue ice packs, the ones with the goo inside a solid plastic <whatever-you-call-a-squashed-cube>. Put your PowerBook on top of it. Unless it's especially warm where you are, a single pack will keep the fan off all day, regardless of how you stress the CPU.



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A simple way to prevent PowerBook fan activation
Authored by: maddys_daddy on Nov 10, '05 10:48:00AM
Better be careful with this one. If you live in a humid environment, this could cause condensation to form inside your PowerBook--and we all know how well moisture and electronics play together.

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A simple way to prevent PowerBook fan activation
Authored by: TrumpetPower! on Nov 12, '05 08:34:34AM

Hmph. Good point. in Tempe, Arizona, it's never a problem. The only time you've got humidity to go with the heat is monsoon season...and the air conditioners you need to make it through the heat also take care of the humidity--which never really gets that bad, anyway.



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Authored by: gshenaut on Nov 10, '05 11:39:21AM

I tried the blue ice trick first, before I thought of slowing down the CPU--it didn't work as well, the fan still came on. But maybe I didn't have the ice bag in the right place.

Greg Shenaut

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A simple way to prevent PowerBook fan activation
Authored by: Auricchio on Nov 10, '05 11:49:00AM
By unplugging the power cable, you also shut down the charging circuitry, which contributes to heat — and fan activation. For the curious, try the free Temperature Monitor program.

EMOJO: mojo no longer workin'

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Authored by: bethri on Nov 12, '05 02:01:39PM

I've had great success with FastAndSlow. It's a MenuExtra which allows you to choose Fast, Slow or Automatic CPU usage for both AC and Battery separately, direct from the menu bar.

I switch to slow CPU whenever I need fan silence and/or longer battery life and can sacrifice full CPU speed to get it. Works perfectly on my 12" PB with Tiger.


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Authored by: igabe on Mar 29, '06 08:04:42AM

You've made me want to hug you.

FastAndSlow is perfect and is going to make using my old powerbook enjoyable again (no more intense burning sensation).

Thank you!

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You can use AppleScript and Temperature Monitor to prevent fan activation
Authored by: jasper vicenti on Nov 30, '05 01:32:45AM

You can also use the terminal (and thus, applescript) to change your settings:

-- fast
do shell script "sudo pmset -c -a dps 0 reduce 0" password "administrator password" with administrator privileges

-- automatic
do shell script "sudo pmset -c -a dps 1 reduce 0" password "administrator password" with administrator privileges

-- slow
do shell script "sudo pmset -c -a dps 0 reduce 1" password "administrator password" with administrator privileges

You will need to change the password to your administrator password. In order to protect your password, you should save as an applescript application and check the box marked "Run Only", which prevents the plain text from being embedded in the app.

Why is this more useful than the FastAndSlow (which I also use)? You can set up Temperature Monitor ( to automatically launch your script if the temperature exceeds or drops below a certain value.

On my PowerBook, I have found the fan turns on at about 138 degrees F, so you can have it launch the "slow" script at 134 degrees (there is a slight delay). This will prevent the fan from turning on for any processes running. I have it set up to switch to "automatic", so that my user processes will still run fast, but niced processes should not cause the fan to turn on by themselves.

I had to run two copies of Temperature Monitor in order to have the two separate scripts run. The second copy is set to launch the "fast" script at 128 degrees F. When properly ventilated, this provides an "effective" processor speed about halfway between the Fast and Reduced settings.

I may write a simple program that can do all of this automatically, but I probably won't have time in the next two months due to other work.


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