[RC5] RC5 on laptops & CPU temperature

SideWinder sidewinder at kolumbus.fi
Fri Nov 5 10:11:49 EST 2004

At 12:52 5.11.2004, you wrote:
>This depends on what the bottom of your laptop is made of. The bottom of 
>my iBook is plastic, and it does get quite warm (though not uncomfortably 
>warm, which is a good thing). Open-air cooling of the underside isn't that 
>much better than none at all, though. But if you want it to run much 
>cooler, levitate it and get a fan to blow air across it (a 50mm fan should 
>be plenty). This works pretty well for my external hard disk, though it 
>requires the case open and the hard disk upside-down and the fan sitting 
>roughly on the spindle.

I've found out that it makes a significant difference for the cooling fan 
speed (and sound tone), whether the laptop rests on its small legs and 
draws the intake air from a small clearing between the bottom and any solid 
surface. If there is more room for the intake air to reach the fan inlet, 
it will decrease the intake air resistance and require less rpm for the fan 
to achieve the same cooling airflow. I don't think it makes that much 
difference with the surface temperature whether there is a few mm of air 
space or nothing at all between the laptop bottom and the surface it's 
sitting on. Even if the surface is aluminium, it probably won't form a good 
enough thermal interface with the laptop bottom to transfer much heat via 
conduction unless there is some other mating material in between. Keeping 
the lid open should allow some heat escape from heating the air in contact 
with the top and perhaps some circulating inside leaking from small gaps in 
the keyboard etc.

>>IIRC the temperature monitoring and pausing works only in Apple G3 and G4 
>>laptops. If you worry about the noise of the fan, you could use a task 
>>scheduler to run "dnetc.com -pause" and "dnetc.com -unpause" in a few 
>>minute intervals.
>It should also be possible to write a program to monitor the CPU 
>temperature (there are plenty of these) and rename the pausefile.

MBM has running external commands as an option for temperature alert 
(although it's not supported anymore).


 >------->- SideWinder -<-------<

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...Computer Science: solving today's problems tomorrow.
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