How to measure temperatures correctly
1. Environment and setup
Before you can do any measurements you need to be in a environment with a relatively steady ambient temperature, like your office, kitchen or living room. Place the computer on a flat table top.
You should be conducting the measurements using these practices:
- The MagSafe plugged in
- Optimization set to Better Performance in the Energy Saver panel
- Brightness turned to full
- Wireless and bluetooth turned on
2. Warming up
Power up the machine and let the temperature of the components inside the machine level off with the surrounding ambient temperature for 10-15 minutes.
3. Software installation
3.1 SpeedIt
To measure the CPU core temperature on an Intel Core Duo on Mac, you have to download and install an kernel extenstion called SpeedIt made by the Increw Team. Make sure to get the latest avaiable version.
There is still not an official way by Apple to access the CPU information. More information on how to install will probably come later...
3.2 Hardware Monitor
This application is used to poll the information from the SpeedIt extension and show it in a nice graphical way. Hardware Monitor will automatically detect if the extension is running in the background. You don't need to buy the application, the demo version will allow you to read temperatures without restrictions.
3.3 (Optional) CoreDuoTemp
To confirm the readings of Hardware Monitor you can run CoreDuoTemp simontanously and compare the two. This application has a very simple interface and will show you three values; CPU temperatures, CPU usage and CPU frequency.
4. Start monitoring
Now start both Hardware Monitor and CoreDuoTemp.
In Hardware Monitor go into Preferences, set the Update Interval to 1 second, in the History tab, add a new temperature history by clicking the +-button, enter a name, select the new temperature history and at the bottom at two sensors. The first is the CPU temperature and the other is the S.M.A.R.T hard drive temperature sensor.
Close the Preferences window and select the Window menu and Show History Windows.
5. Idle temperature
Let the machine idle for 10 minutes without any applications open other than the monitoring applications. The CPU will throttle down while idle even when Better Performance is selected. You can watch this happen with CoreDuoTemp.
If you have excessively many widgets open or other background processes other than what comes with a basic Mac OS X install, try to close these to simulate an average configuration of Mac OS X. This is to avoid incorrect readings of the idle temperature.
After 10 minutes, write down the current idle temperature shown in Hardware Monitor or CoreDuoTemp.
Note: If your temperature does not exceed 30 °C, you are probably affected by the AE18 bug. Read more here.
5. Load temperature
Now it's time to 'torture' the two CPU cores to maximize the thermal heat output.
Go the the Applications folder, then the Utilities folder, and open the Terminal application. Don't worry, it's not as frightning as it looks. Now type the command belwo and press enter:
yes >/dev/null
This will make one CPU core work as fast as it can. But with dual-core processors, there are two CPU processors and ONE application can only work on ONE core at a time. Therefore you need to open a new Terminal window by selecting File -> New and type the command again, like shown below:
yes >/dev/null
To verify that both CPU cores are under load, starting the Activity Monitor application in the Utilities folder. You will see that there are two processes called 'yes' using around '100%' cpu usage each.
Let the machine run for 10 minutes for the temperature to stabilize. You can see the temperature climbing in Hardware Monitor. After 10 minutes write down the current load temperature shown in Hardware Monitor or CoreDuoTemp.
Note: We're not looking for the peak temperature but the average temperature after the fans has kicked in and cooled the machine while under heavy load.
6. Hard drive temperature
Immediately after you've finished the load temperature recording, you can write down the hard drive temperature reported by the S.M.A.R.T sensor inside the hard drive.
7. Submit information
You should now have three different temperature readings; idle, load and hard drive temperature. Go to the submit form and enter this information along with the spesifications of your computer. Make sure to leave a comment.
Thanks for the effort!
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