How to Reboot an Apple iMac to Its Factory Settings

Shutting down or restarting your Apple iMac flushes the contents of its memory, including items you copied to the clipboard and the remnants of operating system and software procedures. A special form of memory called nonvolatile RAM, or NVRAM, stores your Intel iMac's startup settings. 

To reboot your system to some of its factory defaults, perform an NVRAM reset. If you need to restore your iMac to its original configuration, removing sensitive personal and business data so you can prepare the system for resale or reassignment, reboot your iMac and use the Recovery system built in to the Mac OS to return the computer to its factory settings.

NVRAM Reset

Step 1

Open the Apple menu and choose "Restart." A dialog box with a one-minute countdown timer appears, asking if you want to cancel or restart. If you allow the timer to count down to zero, your iMac restarts automatically.

Step 2

Press and hold the "Command" and "Option" keys, along with the letters "P" and "R" before your monitor displays a gray screen.

Step 3

Continue holding down the four-key combination until your system chimes, restarts again and chimes for a second time. Release the keys and allow your iMac to finish restarting.

OS X Recovery

Step 1

Confirm that your computer has access to an active broadband connection. The OS X Recovery feature erases your hard drive and reinstalls a fresh copy of OS X, returning your computer to its factory settings. The process requires a high-speed Internet connection.

Step 2

Open the Apple menu and choose "Restart." A dialog box with a one-minute countdown timer appears, asking if you want to cancel or restart. If you allow the timer to count down to zero, your iMac reboots automatically.

Step 3

Press and hold the "Command" and "R" keys. You must depress both by the time your monitor displays a gray screen. Release them when the Apple logo appears.

Step 4

Click on the "Disk Utility" option in the Mac OS X Utilities window that appears after your iMac reboots. Click on the "Continue" button at the bottom of the window.

Step 5

Click on the "Continue" button on the dialog box that appears. It notifies you that the installer will send your iMac's configuration information to Apple to confirm that your computer can run the OS you're about to install.

Step 6

Launch "Disk Utility" from the set of options that appears after system confirmation. Select your startup disk from the list of available drives and partitions on the left side of the Disk Utility interface. Switch to the Erase tab.

Step 7

Set the format to Mac OS Extended (Journaled). Rename your startup disk, using the default "Macintosh HD" label that appears on new systems. Click on the "Erase" button to begin the process. When you're prompted for it, enter your Apple ID and password. The installer downloads the data it needs and performs the reinstallation.