Target Display Mode between old and new iMacs

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Level 1

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Target Display Mode between old and new iMacs

I have a newer 2017 iMac 27 with Retina 5K, running MacOS 10.13.6. I also have an older mid-2011 iMac 27 also running MacOS 10.13.6. I purchased an adaptor so I could connect the older iMac Thunderbolt port to the newer iMac Thunderbolt 3 port. After connecting them I can't get Target Display Mode to work. I've read that the new Retina 5K doesn't support Target Display Mode, but I thought it was the older iMac that neded to support the mode. Is that correct? Or do both iMacs need to support Target Display Mode?

If the newer iMac won't support it are there are ways to create a dual monitor setup?

Thank you.

iMac Line (2012 and Later)

Posted on Apr 22, 2020 3:34 PM

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Answer 1

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Old Toad

Level 10

208,181 points

Apr 22, 2020 3:50 PM in response to Crash777

Do both Macs meet the requirements listed in this Apple document: Use your iMac as a display with target display mode - Apple Support.

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Answer 2

den.thed

Level 9

78,058 points

Apr 22, 2020 4:00 PM in response to Crash777

Carefully study > Use your iMac as a display with target display mode - Apple Support

It say's you need a Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter,

https://www.apple.com/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter?

and a Mini DisplayPort to Mini DisplayPort cable. (a Tb 2 to Tb 2 cable does not work with the older 2011 iMac)

https://www.bhphotovideo.com/c/product/1213981-REG/newertech_nwtcblmdmm06_mini_displayport_male_to.html/?

https://www.cdw.com/product/StarTech.com-6-ft-Mini-DisplayPort-1.2-Cable-M-M-Mini-DisplayPort-4k-Di/2088983?

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Answer 3

Crash777 Author

Level 1

8 points

Apr 22, 2020 4:04 PM in response to Old Toad

According to that article - yes. But in the article on the Apple site that I linked below, it appears the newer iMac 27 with Retina 5K won't support it.

https://support.apple.com/guide/mac-help/use-an-imac-as-a-display-mh30822/mac

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Answer 4

Apr 22, 2020 5:09 PM in response to Crash777

Use your iMac as a display with target display mode - Apple Support

The 2011 iMac has Thunderbolt, and will not work as a display using a Mini DisplayPort cable, even though the plug will fit. It can use Mini DisplayPort cables and adapters when driving other displays, which may have led to confusion.

The 27" 2009 and 2010 iMacs do use Mini DisplayPort for Target Display Mode, but will not work with the Thunderbolt Adapter. They would need USB-C to Mini DisplayPort adapters or cables.

To use a 2011 iMac as a display you need a Thunderbolt 3 adapter

https://www.apple.com/ca/shop/product/MMEL2AM/A/thunderbolt-3-usb-c-to-thunderbolt-2-adapter

and a Thunderbolt cable.

https://www.apple.com/ca/shop/product/MD861LL/A/apple-thunderbolt-cable-20-m

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Answer 5

Crash777 Author

Level 1

8 points

Apr 22, 2020 4:14 PM in response to den.thed

I have the Thunderbolt 3 (USB-C) to Thunderbolt 2 adaptor, and used it to connect the two iMacs. I see you're saying that I'll also need a Mini Display port, but the newer iMac doesn't have a port for that. So does that mean I need the MDP cable and adaptors to connect the 2 Macs? Seems like a crazy routine to have to go through just to connect a second monitor.

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Answer 6

den.thed

Level 9

78,058 points

Apr 22, 2020 4:25 PM in response to Crash777

You need the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 adapter to plug into the newer iMac and then you need to plug a Mini DisplayPort to Mini Display port cable in-between that adapter and the old iMac.

Personally I have to agree that not only is it a crazy routine, it is also flaky and has far more pitfalls that just connecting and using a standard Display.

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