How to Start the Apple Hardware Test

If you think your Mac has a problem, you can use Apple's built-in Hardware Test to find out the problem. This article shows you how.

Steps:

1. Insert your Installation Disk. This should be the one of the discs from your Mac accessories. If it isn't there, use the latest operating system disc, such as the Snow Leopard installation disk. In OS X Lion, the hardware test is usually stored on the Hard Drive. If it is not found, your Mac will attempt to download the test over the internet.
   
   
2. Shut down and boot up/restart your Mac. Before you hear the chime, hold down D. After the chime, hold it for maybe 2-5 seconds. Then, release it.
3. The screen should start showing weird things. This is normal.
4. After a bit, Apple Hardware Test will display. Click start. The fans may start speeding up and slowing down. This is also normal
5. If no random numbers and letters are displayed, there are no hardware faults, but if there are, there is at least one fault.
6. If you have a fault, call Apple and tell them your fault code.
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