Apple Hardware Test: iMac (Mid 2007) and later models
Summary
Learn how to use the Apple Hardware Test (AHT) diagnostic software with the iMac (Mid 2007) and later computers.
Note: The iMac (Mid 2007) and later model computers come with Apple Hardware Test installed on a separate hard drive partition. This partition is not visible in the Finder.
Products Affected
iMac (20-inch, Mid 2007), iMac (24-inch Mid 2007), iMac (21.5-inch, Late 2009), iMac (27-inch, Late 2009), iMac (24-inch, Early 2009), iMac (20-inch, Early 2009), iMac (24-inch, Early 2008), iMac (20-inch, Early 2008)
To run Apple Hardware Test from the internal hard drive
- Restart your computer while pressing and holding the 'D' key on your keyboard during startup.
Note: If Apple Hardware Test was removed by reformatting the drive, or if you cannot open it from your hard drive, you can still use Apple Hardware Test from the 'iMac OS X Install Disc 1' install DVD that came with your computer.
To run Apple Hardware Test from the Install DVD
- Insert the 'iMac OS X Install Disc 1' install DVD into the optical drive of your computer.
- Restart the computer while pressing and holding the 'D' key on the keyboard during startup.
Note: You can restore Apple Hardware Test to the internal hard drive using the 'iMac OS X Install Disc 1' install DVD that came with your iMac (Mid 2007) or later. To do this, use the Restore feature to reinstall your System Software.
| AppleCare name | Model Identifier | AHT version |
| iMac (20-inch, Mid 2007) | iMac7,1 | 3A125 |
| iMac (24-inch, Mid 2007) | iMac7,1 | 3A126 or 3A127 |
| iMac (20-inch, Early 2008) | iMac8,1 | 3A138 |
| iMac (24-inch, Early 2008) | iMac8,1 | 3A139 |
| iMac (20-inch, Early 2009) | iMac9,1 | 3A156 |
| iMac (24-inch, Early 2009) | iMac9,1 | 3A157 |
| iMac (21.5-inch, Late 2009) | iMac10,1 | 3A176 |
| iMac (27-inch, Late 2009) | iMac10,1 | 3A179 |
Note: You can locate the Model Identifier on your computer using Apple System Profiler:
- Go to the Apple menu and choose About This Mac.
- Click More Info...
- Under Hardware Overview, see Model Identifier.