Open your Terminal and enter the following command followed by hitting the Return key.

yes > /dev/null

This will load your processor and run it at 100%. If you have two processors/cores, open another Terminal window and repeat. This will get both processors/cores running at 100%. Tip: You can monitor your processor(s) in your Activity Monitor.

This test can be useful if you're having a thermal issue that's shutting your computer down. It's also good for monitoring your processor(s) temp(s) under heavy load to see how hot they are running and how the efficient the cooling fan(s) are working.

To stop the test, simply close the Terminal window(s) and the process will terminate sending your processor(s) back to 0.

Here are some CPU temperature monitoring apps.

CoreDuoTemp

Hardware Monitor

miniCPUheat

MenuTemperature

Interesting Dave,

I am able to get the MacBook temp up to about 82C and the fan running strong but on the iMac it still doesn't go over 60 C. and the fans never come on.

I love this iMac!

Also interesting to watch the MB "SpeedStep" the processor between 1.83 and 2.0 to maintain the max temp of 82.

The iMac stays at 2.0 all the time.

Ran it... 72C and no shutdown on AC power.

I did check on the Apple site and my battery is one of the lots affected.... Sooooo.... I'm getting a new one and hopefully will be in good shape again.

Thanks for the quick reply!

MK

You can also use the SystemLoad app to run at 100%.

C