Tip: Diagnostics available without Leopard DVD

With newer Mac models, the Leopard DVD is no longer needed to run the Apple Hardware Test for diagnosing hardware problems. Users can simply boot the computers startup while holding the "D" key down to boot into diagnostic mode -- the utilities are stored somewhere on the hard drive.

One Apple Discussion board user experimented with his setup, and found the system does not boot into diagnostic mode if the hard drive is disconnected. Additionally, it seems this feature is only available on original factory-installed operating systems (or reinstalls from the Apple-provided restore DVDs), so users who have upgraded from Tiger or who have reinstalled their operating systems from retail boxes may not have this feature. Speculation holds that Apple enabled this feature to facilitate diagnostics with the driveless MacBook Air.

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