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[Solved] Hooking up two imacs for dual display.  



Hi everybody. This is my first post so pls forgive me if it appears redundant. I have an imac 2010 (11,3) with a minidisplay port (mdp). I recently purchased an imac 2019 (5K) which has thunderbolt 3 ports (also called USB C) I believe. It also has USB 3 ports, but NO mdp..

I want to connect the two computers to use the older imac as a secondary monitor so that I can have an extended display (not a simple mirroring). Every post I have read talks about connecting the two with a mdp on both ends but the new imac does not have a mdp, not does the old one have a thunderbolt 3 port.

Also all the the mdp I seem to find in stores are mdp to hdmi or VGA, but neither computers has those ports.

How do I connect these two imacs. Do I need to find a mdp with HDMI, then a thunderbolt 3 with HDMI and then connect the two with a HDMI cable?

Any help would be greatly appreciated.

Thanks in advance.


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3 Answers

How to connect 2 imac? No display port. Both only usbc. What cables/adaptor do i need?

By Angel_eidell June 9, 2020 10:19 EDT AM

Use an iMac with Thunderbolt as an external display

Note: Target Display Mode isn’t supported on iMac models with Retina display. Only iMac (27-inch, Late 2009), iMac (27-inch, Mid 2010), and iMac (Mid 2011 to Mid 2014) support Target Display Mode.


Make sure the iMac you want as an external monitor is one of the above, otherwise it will not work.


Can you please advise me if it is any solution to connect 2 IMac late 2009 21.5 inch in a dual display?? Thank you

Re: leo_keresztesiyahoo-com

The 21.5” iMac CANNOT be put into Target Display Mode.

Only certain 27” iMac models, as listed above, support Target Display Mode.

Thank you for your time, I am wondering if it is any convertor or soft that can help me to do this ...Thank you


This cable will work

I got one, and I've successfully used it to connect my Late 2016 15" Macbook Pro (4 USB-C Thunderbolt ports) to my Late 2009 27" iMac in Target Display Mode.

It worked perfectly.

This post was modified 1 year ago by datafornothinandbitsforfree

Thanks for the response. My dilemma is that my 2010 imac does NOT have any USB-C Thunderbolt ports, it only has the mini display port. So the new one and the old one have different ports (the new one the Thunderbolt USB-C one) and my older one only the mini display port. But will check out the cable you suggested. Thanks

Obviously I should check things out first before commenting:) That seems to be the cable that would solve my problems. Much appreciated. Was confused (thought the cable would be one without a mini display port, but looks like it has one), no surprise there. Awesome.Will try it.

My iMac is coming up on 10 years old and cannot upgrade to Mojave, but it still works rather well and the 2K display is actually still a better display than any of the 1080p monitors' work will let me have.

When I saw someone post this cable in the forums saying it worked for USB-C based Macs and older iMacs in Target Display Mode, I clicked on the link and ordered one immediately.

When it came, I connected it from my USB-C based Macbook Pro to my iMac's mini Display Port, the put my iMac into Target Display Mode. It works wonderfully! My iMac was a 2nd display to my Macbook Pro.

And just because I have a strange sense of humor, I started a Screen Sharing session from my Macbook Pro to my iMac, which was still running, and moved the screen sharing session to the Target Display Mode iMac screen and expanded it to "Full Screen".

So the Target Display Mode iMac screen was displaying the iMac desktop, except the desktop, image traveled across an Ethernet connection to the Macbook Pro, which then sent the image across the USB-C Thunderbolt 3 to mini Display Port cable back to the iMac display.


Sorry for probably asking the same question. But before I run and grab this cord, let me just run it past you too.
Have a late 2009 21.5" iMac. Just purchased a new 21.5" iMac. Would the above mentioned cord work to use the older one as a second display?


The old iMac has mini DisplayPort.
The new iMac has Thunderbolt 3 USB-C ports.


The Cable I specified connects a Thunderbolt 3 USB-C port to a mini DisplayPort.


Except for the fact that I have a Macbook Pro with Thunderbolt 3 USB-C ports, we have a very similar setup. I have used the cable I specified to turn my mini DisplayPort iMac into a monitor for my Thunderbolt 3 USB-C based Macbook Pro.