Install El Capitan On External Drive

  1. Download El Capitan installation from the App store. It might complain that you already have it installed but download it anyway. It will be downloaded to /Applications and be named Install OS X El Capitan.app
  2. Create a bootable image from the El Capitan installer on a USB stick larger than 6GB. In a terminal run:
  1. Install El Capitan On External Disk
  2. Create Bootable Usb El Capitan

Note, that to install the Lion or Mountain Lion, your Mac needs to be running Snow Leopard so you can install the newer OS on top of it. How to get macOS El Capitan download. If you are wondering if you can run El Capitan on an older Mac, rejoice as it’s possible too. But before your Mac can run El Capitan it has to be updated to OS X 10.6.8. Then name it El Capitan Type and Version = MAC OS X (64bit) and click on Next. Allocate more than 3GB of ram and click on next. Then click on Use an existing virtual hard disk file and browse for the virtual hard disk file extracted from El Capitan Disk ISO Image and click on Create. Then select El Capitan virtual machine and click on Settings.

Drive

Install El Capitan On External Disk

where MyVolume is the name of your USB stick. Change this to match the name of your USB stick.

  1. Physically install SSD into the target laptop.
  2. Insert the El Capitan USB stick into the target laptop and power up. (This might take a while.)
  3. When the menu finally turns up, choose Disk Utility and format the SSD as Mac OS Extended (Journaled) with a unique name.
  4. Once complete, exit from Disk Utility and return the main menu.
  5. Choose to Install OS X on the formatted SSD.
  6. Follow the prompts until El Capitan is installed.

Here’s link to a video on how to physically install the SSD as well as run the software installation.

Create Bootable Usb El Capitan

If you’d rather install Yosemite on the SSD then follow the How to Install Yosemite on a New SSD guide.