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JacquesleMac

macrumors regular
May 24, 2010
111
115
Oxford, UK

pshufd

macrumors G3
Oct 24, 2013
9,982
14,455
New Hampshire
I’ll get one soon and use our 2014 iMac as a 5k display with a new M1 Mac Mini.

I did a lot of testing this week on using old Macs as a third display for my M1 Mac mini. I am currently using a 2010 iMac 27 as a QHD screen for my M1 Mac mini. The other two monitors are Dell 4k 27 inch panels. I did test my 2014 iMac 27 with this though not at native 5k resolution and I didn't test it fullscreen but it did work. I also tested it with a 2007 MacBook Pro 15 at fullscreen and that worked fine. I also tested it with a 2015 MacBook Pro 15 hooked up to a 4k monitor and that was fine. I can watch YouTube videos at QHD and lower. I do not know if this is the case for 4K and 5K. It's not really my use case as QHD is good enough.

This is just with GB Ethernet. I imagine that wired Ethernet would be pretty good.
 
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zarmanto

macrumors 6502a
Feb 3, 2014
559
481
Around the corner from the 7/11
I just happened to see a parallel conversation on this topic, and went back to lookup an article for my response... this seems like another thread where that link could be relevant:

YouTuber Luke Miani converts a 2014 iMac into an external monitor.

Executive summary: We may not be able to use Target Display Mode... but with a little hardware modding, that perfectly viable screen doesn't necessarily have to go to waste.

Of course, the "perfect" mod in my want-to-have-my-cake-and-eat-it-too mindset would be one which enables me to switch between displaying a signal from my existing internal Mac hardware and displaying one from an external input. In Miani's build, he basically guts his iMac entirely to perform the conversion; there's no longer a "Mac" in that iMac shell when he's done with it. It's absolutely fascinating stuff... but it also kind'a hurts my heart just a little bit to watch. o_O
 

pshufd

macrumors G3
Oct 24, 2013
9,982
14,455
New Hampshire
I just happened to see a parallel conversation on this topic, and went back to lookup an article for my response... this seems like another thread where that link could be relevant:

YouTuber Luke Miani converts a 2014 iMac into an external monitor.

Executive summary: We may not be able to use Target Display Mode... but with a little hardware modding, that perfectly viable screen doesn't necessarily have to go to waste.

Of course, the "perfect" mod in my want-to-have-my-cake-and-eat-it-too mindset would be one which enables me to switch between displaying a signal from my existing internal Mac hardware and displaying one from an external input. In Miani's build, he basically guts his iMac entirely to perform the conversion; there's no longer a "Mac" in that iMac shell when he's done with it. It's absolutely fascinating stuff... but it also kind'a hurts my heart just a little bit to watch. o_O

That's exactly what I have right now.

I have the iMac as a display on the M1 mini but I can just hit Control-Left to get back to the iMac itself and run off of it directly. The iMac is actually a very nice system. CPU is decent though not strong. Fine for watching videos and the remote control works for music and videos. I mainly use the M1 mini for professional stuff but can just turn it off outside of work hours.

The problem with the Luke Miani fix is that it's no longer a computer.

My 2010 iMac actually does have Target Display Mode. But this other approach allows me to use it as a third display off a low-end M1 computer.
 

zarmanto

macrumors 6502a
Feb 3, 2014
559
481
Around the corner from the 7/11
That's exactly what I have right now. ... My 2010 iMac actually does have Target Display Mode.
That's all well and good, but given that newer iMacs simply don't have that option, I was kind'a alluding to the pie-in-the-sky notion of performing such a multipurpose conversion on my 2019 iMac. That way, I could continue to use what is actually a very nice iMac in its own right, as well as leverage that 5K screen for an alternate computer, be that an Apple Silicon system or a Windows box or whatever else I might have handy.

And honestly, I would even be hesitant to summarily gut my older 2012 iMac, as I would no longer be able to continue using those Mac internals. It may not quite meet the needs of certain modern games, but it nonetheless still performs many other tasks quite reasonably, and I would hate to give that up. For example, my father-in-law uses it daily to work from home, (Bootcamped into Windows) as he says that it's actually much faster than his two-year old Windows PC... and amusingly enough, what he doesn't know is that the iMac he's praising just happens to also be hosting a small Minecraft server in the background, while he works. :cool:

But if I could also use that reliable old 2012 iMac as a monitor for the even older Mini Server sitting behind it? Oh, heck yeah.
 

pshufd

macrumors G3
Oct 24, 2013
9,982
14,455
New Hampshire
That's all well and good, but given that newer iMacs simply don't have that option, I was kind'a alluding to the pie-in-the-sky notion of performing such a multipurpose conversion on my 2019 iMac. That way, I could continue to use what is actually a very nice iMac in its own right, as well as leverage that 5K screen for an alternate computer, be that an Apple Silicon system or a Windows box or whatever else I might have handy.

I think that I can get it to work on 5k iMacs as well. I've already done a proof of concept at scaled HD on my 2014 iMac 27. And I can switch between the iMac and the M1 mini on it. The M1 mini display is actually just a space so I can just use control-left or control-right to move back and forth between the iMac and the M1 mini.
 

pshufd

macrumors G3
Oct 24, 2013
9,982
14,455
New Hampshire
I must have missed something... are you talking about a software solution or a hardware hack?

This is a software solution for 2K. I am running it right now using my 2010 iMac 27 as a third monitor for my M1 Mac mini and I'm using this solution for production. The virtual monitor is actually just a Space. I can just flip over to the iMac as just another space.

I am going to try it with 5k as a software only solution but I don't expect it to run well unless running 5k in scaled mode. It's possible that that will work but I don't know. The ultimate solution would be to buy a Thunderbolt 3 to Thunderbolt 2 adapter and Thunderbolt 2 cable to create a high-speed network between the two systems which would provide enough bandwidth for 5k.

I have tested this out with a couple of M1 systems (2020 M1 Mac mini, 2021 M1 Pro MacBook Pro 16) running displays on several old Macs: Late 2009 iMac 27, Late 2010 iMac 27, 2007 MacBook Pro 15, Mid-2015 MacBook Pro 15 and 1,920 x 1,200 resolution on the Late 2014 iMac 27. The nice thing about this solution is that you can use equipment that doesn't support Monterey. Otherwise I could just use AirPlay.
 

zarmanto

macrumors 6502a
Feb 3, 2014
559
481
Around the corner from the 7/11
This is a software solution for 2K. ...
Ah; got it.

Yeah, that's a really interesting project which will certainly have a lot of value for some users -- but as a software solution, it's not quite what I had in mind. A hardware mod such as what I was describing would of course eliminate the bandwidth and performance concerns that you're attempting to work through -- but in truth, that mod doesn't appear to exist in a form which retains the full original functionality of the modded iMac. That's why I characterized it as pie-in-the-sky.
 

pshufd

macrumors G3
Oct 24, 2013
9,982
14,455
New Hampshire
Ah; got it.

Yeah, that's a really interesting project which will certainly have a lot of value for some users -- but as a software solution, it's not quite what I had in mind. A hardware mod such as what I was describing would of course eliminate the bandwidth and performance concerns that you're attempting to work through -- but in truth, that mod doesn't appear to exist in a form which retains the full original functionality of the modded iMac. That's why I characterized it as pie-in-the-sky.

Target Display Mode gives you video and sound. It is possible to do the sound output with a software solution but I don't know about videocamera and microphones. I have the monitor working and I find it quite useful and use my 2014 iMac if I need monitor, videocam, speakers and microphones. What I do like about the software approach is that you can use really old MacBooks as additional monitors.
 

jhencken

macrumors member
Jul 17, 2011
33
0
University Place, WA
I've been on the fence about getting a new iMac for a while already, and now with the newly announced Mac Studio I think I'm just going to get that.

But it would be great if Apple would let us use our older 27 inch iMacs simply as a screen for the Mac Studio. I think they did that with the very old generations of iMac. And now that it seems that the 27 inch iMac will be discontinued (not sure ofcourse), it would be nice of apple to allow this via software.

Thoughts? The 27 inch iMac is a beautiful screen. It would be a shame to not put it to good use.
I share your frustration. I have a Mac Studio M1 and several old iMacs with great screens. Latest options I've seen are Duet software, Luna dongle+software, and an HDMI plugin that creates a virtual display

(see: https://www.amazon.com/Headless-Emu...7e19e542ff&ref_=pd_gw_ci_mcx_mr_hp_atf_m&th=1)

IDK if the last option works. Anybody tried it?
 

Eric Best

macrumors member
Jul 30, 2011
34
6
Tamworth, NSW, Australia
I've used Duet to use my 2013 iMac screen with my Mac Studio via WI-FI. I'm not sure how well it compares with the Luna solution. I'd like to know others' experience with both approaches!
 
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