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OS X El Capitan: Use another Mac as a display

Use another Mac as a display

You can view your Mac’s desktop on the display of another Mac using Target Display Mode. In some cases, you can also use Target Display Mode to play the sound from your Mac (called the “primary Mac”) on the speakers of the external Mac. For example, if you have a a MacBook Pro you could use a 27-inch iMac as the display and play its audio on the iMac as well.

After you connect the computers and turn on Target Display Mode, the external display Mac acts like any other external display. Apps that were open on the external display Mac remain open even though you can’t see their windows.

Use an iMac with Thunderbolt as an external display

If you have an iMac with Thunderbolt, any other Mac with Thunderbolt can use it as a display. The iMac will play both the video and audio from the other Mac.

Connect the Thunderbolt cable to the Thunderbolt ports on each computer.
Make sure both Mac computers are turned on and awake.
Press Command ⌘-F2 on the keyboard of the external display Mac.
If you want the Mac to play audio as well as video from the primary Mac, go to the primary Mac, choose Apple menu > System Preferences, click Sound, then click Output.

Then select the Mac in the list of devices.

Use a 27-inch iMac with a Mini DisplayPort as an external display

If you have a 27-inch iMac with a Mini DisplayPort , any other Mac with a Mini DisplayPort or Thunderbolt port can use it as a display. Make sure you have a Mini DisplayPort to Mini DisplayPort cable.

If the primary Mac has a Thunderbolt port, it can play audio and video on the iMac. If the primary Mac has a Mini DisplayPort, it may be able to play its audio. To see if it can, go to the primary Mac, choose Apple menu > About This Mac, click System Report, then select Audio in the Hardware category. A list of your computer’s audio devices appears. If HDMI Output or HDMI/DisplayPort Output is listed, your computer’s Mini DisplayPort can send audio. Make sure you use a Mini DisplayPort cable that carries both audio and video.

Connect the Mini DisplayPort cable to the ports on each computer.
Make sure both computers are turned on and awake.
Press Command ⌘-F2 on the iMac.
If you want the iMac to play audio as well as video from the primary Mac, choose Apple menu > System Preferences, click Sound, then click Output.

Then select the iMac in the list of devices.

Turn Target Display Mode off

You can easily turn Target Display Mode off without disconnecting the computers.

Turn Target Display Mode off: Press Command ⌘-F2 on the keyboard of the external display Mac.

When Target Display Mode is off, the external display Mac displays its own open apps.

Learn what happens when the primary Mac goes to sleep and wakes up

The external display Mac behaves differently depending on how the primary Mac goes to sleep.

If you put the primary Mac to sleep: After you put your Mac to sleep, the external display Mac goes dark for a few seconds and then displays the windows for its own apps. If the external display Mac does not display the windows for its own apps, press Command ⌘-F2 on its keyboard.
If the primary Mac goes to sleep because it was idle: The external display Mac goes dark and stays dark. If you want the external display Mac to display the windows for its own apps, press Command ⌘-F2 on its keyboard.

If the external display Mac doesn’t show the right desktop after it wakes up: When the primary Mac wakes up, the external display Mac displays the windows for the apps on the primary Mac. If it does not, press Command ⌘-F2 on the keyboard of the external display Mac.