Apple: Hardware test - how to check the Mac

If you want to take a close look at your Mac and test it with a number of diagnostic functions, the Apple hardware test will help you. This will show you whether a problem is hardware-related and which components are responsible.

How exactly does the Apple hardware test work?

The exact way the test is started depends on the version of your operating system. Before OS X Lion 10.7, the test has to be started manually. For the newer versions, this happens via the Internet.

1. The first thing you should do is disconnect all peripheral (external) devices from your Mac. So disconnect all mice, keyboards and monitors that are directly connected to the Mac.
2. It is important that the Mac is always well ventilated, so that the program can correctly detect the error.
3. Now shut down the Mac and then turn it on again. While booting up, hold down the D key until the Apple hardware test icon is displayed.
4. Now you just need to select the language and click "Test" to run the test.
5. After running it, you will see the results in the bottom right corner of the window.
6. If you have a newer operating system, the hardware test will be run over the Internet. However, starting the test works the same way. However, there must be an Internet connection via WLAN or LAN.