I have a late 2009 27" iMac, but recently the internal hard drive completely died. When I try to power it up, the iMac gets stuck on the white Apple loading screen. So instead I would now like to use it just as a display.

Is there a way to do this without replacing the internal hard drive? I have used it as a display before when it was working, so I know it can be used that way.

1 Answer 1


If your main priority is just not to replace the HDD, why not install macOS onto a USB flash drive and use that purely so you can use the iMac in Target Display Mode?

To do this, follow these steps:

  1. Boot your iMac from the USB flash drive
  2. Ensure the other Mac is also booted up and logged into a user account
  3. Connect the two Macs with a Mini DisplayPort or Thunderbolt cable
  4. Press Command F2 on the keyboard of the iMac (i.e. The one you want to use as a display).

For more information you should read Use your iMac as a display with Target Display Mode

  • Yes I was thinking of doing this, but I posted this just incase that there was another solution. Could you tell me more about booting off a USB? I know how to install an OS off a USB but not about using the USB as a replacement for the HDD. Mar 12, 2017 at 4:01
  • Take a look at How to set up and use an external Mac startup disk. Keep in mind that any macOS version from Snow Leopard 10.6.1 supports Target Display Mode, although depending on your exact model of 27" 2009 iMac, it may not support booting from an OS earlier than Snow Leopard 10.6.3.
    – Monomeeth
    Mar 12, 2017 at 4:32

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