The Toasty Apple 
Wednesday, 17 June, 2009, 12:30
Posted by Administrator
During the day I like to watch Daisy via my MacBook Pro's webcam. It's really a simple setup -- I set up a Skype account specifically for "Puppy Cam" use and added my MacBook Pro to my LogMeIn Free account. Then, from work, I connect to the MacBook Pro via LogMeIn, dial my Skype account from the laptop, and enable video sharing.

The problem is that the laptop appears to get quite hot if I'm connected to it all day. It's no wonder -- Skype uses a ridiculous amount of CPU time when I'm sharing audio and video. As I type this, it's using between 64.5 and 80% of the system's dual-core CPU. I stream classical music for her using iTunes, and this uses about 4% of the CPU, which isn't much but you're still looking at 84% of CPU usage. This drove the temperature quite high -- north of 80 degrees C, I found out -- which is quite unhealthy for a laptop CPU.

I did a quick Google search and found that the acceptable operating temperature range for a MacBook Pro under load is 120 to 190 degrees F, but I'm pretty sure letting the laptop run for extended periods of time at the top end of that range is frowned upon. At the very least, I don't like doing that.

In response to this unhealthy behavior, I downloaded and installed the latest version of smcFanControl (free download at This application allows a user to manually set their Mac's fan speeds. I noticed that the temperature jumped quite quickly when I started the video stream and, in response, I started increasing the fan speed. Bumping it up from 1800 to 2500RPM made an immediate difference, dropping the temperature from a toasty 78C to 72C which, while still quite hot, is much nicer. I turned the RPMs up to 4500 and this is keeping the processor at an acceptable 60C (140F) while introducing minimal fan noise into the audio stream.

Cranking the fan up to maximum speed, 6000RPM, results in marginally cooler temperatures, but not cool enough to justify running the fan at full speed all day. After 10 minutes of running the fan at max speed, the processor cools down to 56.1C -- definitely better than 60C, but much louder than 4500RPM.

You all knew I was a nerd, but you didn't know how far it went :)
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