How to measure heat output

Question

Level 1

8 points

How to measure heat output

I have a new MBP 2.4 and have been experiencing what I thought might be excessive heat. Looking around this board I find references to how hot it gets.

I would lik to know
1) how you find out how hot the box is.
2) what is an allowable temperature range
3) is there some way to manage the fan?

thanks for responses.

macpro 15" 2.4, Mac OS X (10.4.10)

Posted on Aug 22, 2007 2:02 PM

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Answer 1

Best reply

Kappy

Level 10

361,741 points

Aug 22, 2007 3:29 PM in response to seattlex

First, all MacBooks and MacBook Pros run hot. It's the result of cramming heat generating components in a small volume. If you read the Safety information in your User Guide you will find that it warns not to use the computer on your lap or in an environment without adequate ventilation.

Most people are using utilities such as Hardware Monitor to measure core temperature and fan speed.

There are two utilities to control the fans:

smcFanControl
FanControl

You will find them at VersionTracker or MacUpdate. These utilities are third-party, un-authorized by Apple, and misuse can damage the computer.

In general there is little need to manage the fan because they are already under firmware control. The above referenced software is only able to increase or decrease the fans' idle speeds and nothing else.

Normal CPU core temperature range is 45-85ºC as a function of CPU load. Thermal shutdown occurs at 125ºC.

For more information search the forums because this topic has been covered in excess.

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Answer 2

JASimon

Level 2

290 points

Aug 22, 2007 5:29 PM in response to seattlex

The scientifically accurate way to measure heat output is to place a carefully measured volume of water in an insulated container and wait till it reaches thermal equilibirum.

You then submerge your MacBook Pro in the tub of water and operate it as per normal and measure the increase in the temperature of water.

From this you can calculate the precise heat output from your laptop.

For more information consult this webpage for details. (NB You may need to use a styrofoam esky rather than styrofoam coffee cups for your MacBook Pro measurements.)

PS 😉

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Answer 3

Kappy

Level 10

361,741 points

Aug 22, 2007 5:35 PM in response to JASimon

No doubt with a little search effort we might find a dryer method. For example, we might wrap the computer in a lead container of known mass and then apply the same technique as used with water.

Of course both methods will require testing in a vacuum or using the necessary instruments to take into account ambient room effects plus evaporative effects.

A high quality calorimeter is a must.

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Answer 4

Nashlore

Level 1

0 points

Aug 23, 2007 4:02 AM in response to Kappy

I believe it is much better to undervolting your CPU, thereby decrease the CPU heat. You will not loose any performance from undervolting. CoolBook is the software to look for.
However, it currently do not fully support Santa Rosa.

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Answer 5

Aug 23, 2007 4:13 AM in response to seattlex

You can easily measure the surface temperature of the MBP with an infrared thermometer.

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