CPUTest

CPUTest is an application that can stress-test your CPU. The app is a graphical user interface for the self-test command Glucas.

What this app does is give work to your processor so that you can see how well it works and how its cooling system reacts to an increase in temperature due to the tests.

There are a few configuration options that let you customize the tests. On the main window, you will see three drop-down menus: Test type, Repetitions and Instances. By using those in different combinations, you can change the way the app stress-tests your processor. For example, by default, the test takes a little under 30 seconds. It is a small test type with only 1 repetition and 1 instance. My Macbook Pro didn't even blink at that one, so you may want to gradually increase the intensity until you get your desired results.

Personally, I have suffered from many CPUs dying on me because of overheating problems. So, I am a little reluctant to trying the more intense tests. So, try at your own risk.

CPUTest is absolutely free and it is a universal binary, so it should work on all types of modern Macs.