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Imac as second monitor

Do I need to have installed High Sierra to use an Imac as second monitor?

Posted on Sep 20, 2020 3:05 AM

Reply
12 replies

Oct 13, 2020 9:00 AM in response to Malcolm J. Rayfield

Malcolm J. Rayfield wrote:

What is not mentioned is that a 2020 Mac will work for Target Display Mode with a 2009 or 2010 27" iMac.


HI Malcolm,


A bit of clarification: Users accidentally discovered that those two models worked as monitors with PCs and, apparently, even some gaming platforms. Apple never supported or documented that use.


Now, it appears whatever odd hardware flexibility in those old models that allowed that quirk of compatibility may permit them to work with 2020 Macs based on one thread here:


https://discussions.apple.com/thread/251704486


Interesting read. Based on his activity in other threads about different subjects, the OP of that one seems more than capable. Therefore I am not quick to discount it, although some responders with 2009-10 iMacs say that they cannot make it work. Maybe the others are not as good at figuring out the messy cable issues.



Allan

Oct 13, 2020 8:40 AM in response to joana303

Seems that there's a lot of people with the same problem, and Apple is not solving it


Call this a COVID phenomenon. Prior to COVID we saw maybe two posts a month asking about Target Display Mode (TDM). Nobody cared and it was obviously headed to"fossil" mode.


History: Apple began the deprecation of TDM SIX years ago with the withdrawal of external monitor capabilities for the Late 2014 iMacs. They completed the deprecation early this year (before COVID) by removing the ability of 2020 Macs to be the SOURCE for a video signal sent to an older iMac supporting TDM. They also archived the TDM support article before COVID.


Current sit-rep: That was before COVID Now that we live in a COVID world we are seeing six or more posts per day asking about TDM as people work and study from home. As the deprecation appears to be hardware-based, I do not see a "send out a patch" fix.


....but the most important is not mentioned in the link above, is that it wont work on Macbook pro 13" 2020.


Maybe it ran through the Department of Obfuscation but I spotted the change in the tech article right away:



It comes down to one question: "Could Apple have reasonably foreseen a pandemic sending millions to work from home, and stopped a deprecation process that had been in progress for six years?" I think the answer is no.

Sep 20, 2020 4:13 AM in response to joana303

Any iMac newer than a late 2014 iMac cannot be used in Target Display mode.

Also note, that a 2020 iMac will not work with any Target Display Mode capable

iMac with Thunderbolt ports. Only the late 2009 and 2010 iMacs with mini display

ports can be used with the correct adapter.


Other than that, yes, you must install a version of macOS High Sierra or older.

Oct 13, 2020 2:29 AM in response to Androish

Thank you for you reply.

I couldn't get it done anyway.

There is A LOT of requirements for it to work, software, cables, adapters, year of iMac model, but the most important is not mentioned in the link above, is that it wont work on Macbook pro 13" 2020.

Seems that there's a lot of people with the same problem, and Apple is not solving it..


Thanks again for your reply, even i couldn't make it work, it was indeed helpful.


Best R.


Oct 13, 2020 7:52 AM in response to joana303

I think you may be missing the point, iMacs are computers and are not intended to be used as external displays for other devices. Rather than messing around spending your money on expensive cables and criticizing Apple, why not buy an external display and connect it. You will be up and running in minutes and external displays have come way down in price so the money saved by not buying expensive cables and connectors can go towards your new external display.

Imac as second monitor

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