Imac as second monitor

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

Joana303,

You are not addressing Apple in these forums. We are all end users just like you. Apple is simply our host and does not read or participate in these forums.

If you want to convey your feedback to Apple please do so at www.apple.com/feedback.

Yes you need to have High Sierra or older on the iMac working as a screen

See:

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

For requirements.

Good luck!

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.

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.

It is mentioned in the link:

"You can connect any of these older iMac models to another Mac from 2019 or earlier"

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

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.

Okay, I just wanted you to know that we don't represent Apple and do not communicate with them in any other method that all users have the ability to.