Using Apple Hardware Test
If you suspect a problem with the MacBook hardware, you can use the Apple Hardware
Test application to help determine if there is a problem with one of the computer’s
components, such as the memory or processor.
To use Apple Hardware Test:
Disconnect all external devices from your computer except the power adapter.
If you have an Ethernet cable connected, disconnect it.
Restart your MacBook while holding down the D key.
Problem, Meet Solution
When the Apple Hardware Test chooser screen appears, select the language you want
Press the Return key or click the right arrow button.
When the Apple Hardware Test main screen appears (after about 45 seconds), follow
the onscreen instructions.
If Apple Hardware Test detects a problem, it displays an error code. Make a note of the
error code before pursuing support options. If Apple Hardware Test doesn’t detect a
hardware failure, the problem may be software related.
If this procedure doesn’t work, you can insert the Applications Install DVD and hold
down the D key to use Apple Hardware Test.