Perform a Clean Install of OS X Mountain Lion on Startup Drive

Performing a clean install of OS X Mountain Lion on your startup drive gives your Mac a fresh start with a new system free from accumulated clutter and potential issues. Here’s a detailed guide on how to safely and effectively perform a clean installation.

Preparing for Installation

1. Create a Bootable Installer: Since you can’t erase and install on the same drive without bootable media, you’ll first need to create a bootable installer for OS X Mountain Lion. Use an external drive or USB stick for this purpose.
2. Back Up Your Data: Ensure that you have a full backup of your data, as a clean install will erase all the data on the startup drive. Use Time Machine or another backup method to secure your files.
3. Check Compatibility: Verify that your Mac meets the minimum system requirements for OS X Mountain Lion. You’ll need a Mac running OS X Snow Leopard 10.6 or later to access the Mac App Store to download Mountain Lion.
4. Prepare Your Mac: Ensure that your Mac is plugged into a power source and connected to the internet. This is important as the installation process may require downloading additional components.

Steps to Perform a Clean Install

1. Restart Your Mac with the Bootable Installer:
   • Insert the bootable media.
   • Restart your Mac while holding down the Option key.
   • Select the bootable installer from the startup manager and press Enter.
2. Erase Your Startup Disk:
   • Once booted from the installer, choose ‘Disk Utility’ from the OS X Utilities menu.
   • Select your startup disk, usually named ‘Macintosh HD’, from the sidebar.
   • Click the ‘Erase’ tab and choose ‘Mac OS Extended (Journaled)’ from the format options.
   • Click ‘Erase’ to format the drive. Confirm your decision when prompted.
3. Quit Disk Utility:
   • After erasing the disk, quit Disk Utility to return to the OS X Utilities selector.
4. Install OS X Mountain Lion:
   • Choose ‘Reinstall OS X’ from the OS X Utilities menu.
   • Click ‘Continue’ and follow the prompts to begin the installation.
   • The installer will download necessary files from Apple’s servers. Follow the on-screen instructions to complete the installation.
5. Setting Up Your Mac:
   • Once the installation is complete, your Mac will restart.
   • Follow the setup assistant to configure your Mac. This includes setting up your location, Apple ID, and other preferences.
   • If you opted to back up your data, you can now use Migration Assistant to transfer your data back to your Mac.

Post-Installation

• Check for Updates: After installation, check for any software updates by going to the Apple menu > Software Update. Install any available updates to ensure your OS is current.
• Restore Your Data: If you backed up your data, use Migration Assistant or manually move your data back onto your Mac.

Tips and Considerations

• Creating a Bootable Installer: You might need to use third-party software or terminal commands to create a bootable installer. Make sure your external drive or USB stick has at least 12GB of available space.
• Internet Connection: A stable internet connection is crucial during the installation process as the system may need to download additional components.
• Power Supply: Keep your Mac connected to a power source throughout the installation process to prevent any interruptions due to power loss.

Performing a clean install can enhance your Mac’s performance and provide a fresh version of the OS free from legacy issues. Always ensure you have a reliable backup before proceeding with the installation to safeguard your data.