Setting up iMac as second display/monitor

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Level 1

9 points

Setting up iMac as second display/monitor

I currently am using a 5K Retina, 27-inch, 2019 iMac (Version 10.14.5) and am trying to use an old iMac as a second display/monitor. My old iMac is a 21.5-inch, Late 2015 iMac (Version 10.13.6). I tried going into the admin user on the old iMac and pressing Cmnd-F2 but nothing happened. The two computers are connected by a thunderbolt cable (compatible with the old iMac) and a Thunderbolt 3 to Thunderbolt 2 Adapter (to be compatible with the new iMac). Nothing seems to be happening and I have searched everywhere in the settings and online and cannot find a solution. Please let me know if you know how to fix this. Thanks.

iMac 27", macOS 10.14

Posted on Jul 24, 2019 9:48 AM

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Answer 1

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den.thed

Level 9

78,310 points

Jul 24, 2019 10:07 AM in response to arash228

Please review the system requirements, at > Use your iMac as a display with Target Display Mode - Apple Support

which say's that, "iMac (Retina 5K, 27-inch, Late 2014) and later iMac models can't be used as Target Display Mode displays"

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Answer 2

den.thed

Level 9

78,310 points

Jul 24, 2019 12:35 PM in response to arash228

There are third party VNC's like Real VNC or VNC Viewer, plus macOS's built-in Screen Sharing, but all tend to be somewhat sluggish.

https://support.jumpdesktop.com/hc/en-us/articles/216425923-Mac-How-do-I-enable-the-VNC-Server-built-into-the-Mac-

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Answer 3

arash228 Author

Level 1

9 points

Jul 29, 2019 5:21 AM in response to den.thed

Thank you I appreciate your help. I've been using screen sharing as you suggested for now until I can set up a VNC. It's just been annoying to have to keep the window open and click on it to go to the second monitor which is still just the second computer not a second display. It doesn't make sense why Apple doesn't support these iMacs for Target Display Mode even though they both have updated software and are properly connected. Wires alone cost like 90 bucks and it's still not compatible :/

Anyways, thank you for your help and references.

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