IMac Reset - How to Factory Reset Your iMac Without a CD

= How to Factory Reset Your iMac Without a CD =

Performing a factory reset on an iMac is a bit more involved now because of a hardware omission: The computer no longer is equipped with a built-in optical disc drive. Even if you have the OS reinstallation DVD, it won't do you any good unless you have an external optical drive connected to the system. The iMac features two methods to wipe all hard drives and reinstall the operating system: One uses the built-in recovery partition and the other uses the OS image on a USB flash drive. Both factory-reset methods require an active broadband Internet connection.

Items you will need

 * 4GB or larger USB flash drive (optional)
 * Broadband Internet connection

How to Factory Reset an iMac Via the Recovery Partition
Step 1 Restart the iMac and hold the "Command-R" keys while the computer reboots.

Step 2

Select and connect to a Wi-Fi network from the list if the iMac prompts you to do so.

Step 3

Choose the "Disk Utility" option from the list and click "Continue."

Step 4

Select the hard drive on which Mac OS X is installed from the tree list on the left side of the window.

Step 5

Open the "Erase" tab.

Step 6

Select "Mac OS Extended (Journaled)" from the "Format:" drop menu and enter a name for the hard drive in the "Name:" text entry field.

Step 7

Click "Erase..." to clear all of the hard drive's contents.

Step 8

Choose the "Quit Disk Utility" option to exit the disk formatting tool.

Step 9

Select "Reinstall OS X" from the menu, click the "Continue" button and follow the on-screen instructions to complete the OS installation process on your clean hard drive.

How to Factory Reset an iMac Via Bootable USB Recovery Drive
Step 1 Download the version of Mac OS X the iMac is running from the App Store.

Step 2

Open the "Applications" directory in Finder

Step 3

Control-click on the "Install Mac OS X Lion" icon and choose the "Show Package Contents" icon.

Step 4

Expand the "Show Package Contents" folder.

Step 5

Copy and paste the "InstallESD.dmg" file to an easily accessible location on the iMac hard drive.

Step 6

Open the "Disk Utility" within the Utilities folder under Applications and connect the USB flash drive to one of the ports located on the back side of the iMac.

Step 7

Choose the flash drive from the left-side tree display.

Step 8

Click the "Burn" icon.

Step 9

Select the "Image..." button, then locate and choose the "InstallESD.dmg" file.

Step 10

Click "Restore" to create the restoration drive.

Step 11

Restart the iMac after the restore drive is completed and hold the "Command-R" keys until the boot selector appears.

Step 12

Choose the flash drive from the boot selector.

Step 13

Open the "Disk Utility" and select the iMac's hard drive.

Step 14

Select the "Erase Tab," set the "Format:" value to "Mac OS Extended (Journaled)" and then click the "Erase" button.

Step 15

Quit the "Disk Utility" tool when the hard drive format is complete.

Step 16

Choose the "install Mac OS X" option from the menu and follow the on-screen instructions to complete the factory reset.

Source: http://everydaylife.globalpost.com/factory-reset-imac-cd-30683.html