2011 27" iMac as second display for 2020 iMac

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Level 1

5 points

2011 27" iMac as second display for 2020 iMac

I just purchased the new 2020 iMac and I would like to use my old 2011 iMac as a second display but nothing it working to put the old iMac in Target Display Mode. Everything I see suggests it's capable but nothing works. I'm running High Sierra on the old. I have a Thunderbolt cable into a Thunderbolt 3(USB-C) to Thunderbolt 2 adapter into the 2020 iMac. I've tried restarting, safe mode, on the login screen of the old iMac. Please help!

iMac 27″, macOS 10.13

Posted on Aug 30, 2020 12:26 PM

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Answer 1

Top-ranking reply

Indoor_Astronaut

Level 1

15 points

Aug 30, 2020 2:19 PM in response to tfahey1

TLDR; TDM is not supported by the 2020iMac.

Tried this myself two weeks ago when I got my 2020 iMac. I used to run this configuration with my 2019 and 2012 iMac. You can have all the correct cables and software versions but it will never work because the ability to support TDM was dropped from the 2020 iMac.

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Answer 2

RAMSKULL

Level 1

14 points

Aug 30, 2020 2:45 PM in response to Indoor_Astronaut

That is a huge bummer! Why the removal of such useful & desirable capabilities, is beyond me. So will it only work with basic display only systems, projectors, & such while excluding desktops like iMac? What does TLDR & TDM stand for? *Not that anyone cares but I’d prefer a couple USB A ports, a Mini DisplayPort, & an SD Card slot; all be left as options on all Macs (and a DVD SuperDrive in Macs with built-in displays).

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Answer 3

Aug 30, 2020 5:15 PM in response to RAMSKULL

I agree, very disappointed they dropped support for this feature. I was using it previously and loved it because I am still using the old iMac as a server.

I called Apple Support, the Specialist escalate the issue, I was told Target Display Mode (TDM) support was dropped from the 2020 hardware. You'll need a standard external monitor configuration.

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