brookter1

macrumors regular
Original poster
Aug 5, 2015
108
77
I currently have a 2011 27" iMac, and I've just ordered a 2017 27" iMac (the 3.8GHz version with 580/8GB vram).

I'd like to use the older iMac as an external display for the new one. As far as I can tell from reading around, I can do this (ie both computers are capable of doing it), but need the following:

1. A Thunderbolt 3 (USB C) to Thunderbolt 2 adapter
2. A Thunderbolt cable
3. Keep a keyboard attached to the old iMac to turn Target Display mode on.

Have I forgotten anything / misunderstood anything?

Also, as the older iMac will still be running, I presume I will still have full access to its SSD and internal HD while it's in Target Display mode -- will they effectively be network drives for the newer Mac?

TIA.
 
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brookter1

macrumors regular
Original poster
Aug 5, 2015
108
77
Yes, I'm expecting the drives to appear as shared drives (much as I can access them from my laptop).

I've seen those links -- thanks. I just wanted to confirm my understanding that I've got everything I need.

Cheers.
 

marcolin

macrumors newbie
Oct 9, 2013
15
1
Milan, Italy

According to this page thunderbolt 3->2 adapter + thunderbolt 2 cable does not support DisplayPort video, despite having the same connector. Can anyone confirm if is this true?

other possible option could be an usb-c to mini display port cable like this

Does any forum member has a similar setup already working?
[doublepost=1511619726][/doublepost]
I currently have a 2011 27" iMac, and I've just ordered a 2017 27" iMac (the 3.8GHz version with 580/8GB vram).

I'd like to use the older iMac as an external display for the new one. As far as I can tell from reading around, I can do this (ie both computers are capable of doing it), but need the following:

1. A Thunderbolt 3 (USB C) to Thunderbolt 2 adapter
2. A Thunderbolt cable
3. Keep a keyboard attached to the old iMac to turn Target Display mode on.

Have I forgotten anything / misunderstood anything?

Also, as the older iMac will still be running, I presume I will still have full access to its SSD and internal HD while it's in Target Display mode -- will they effectively be network drives for the newer Mac?

TIA.

I was about to post a similar request since I am in the same situation (new 2017 5K 27" iMac just ordered, late 2012 non-retina iMac soon to be downgraded as secondary monitor) so I will follow this thread.

I have now a similar dual iMac setup (2012-2009) and regarding 3. i suggest you to use 1Keyboard app (or similar): this way you will be able to toggle target display mode on secondary iMac with a single keyboard (via bluetooth).

using screen sharing you will be able also to control the secondary iMac trough your primary iMac (in a smaller window or also full screen on secondary monitor -- this means that you will be able to control your secondary iMac on its own monitor but via your primary iMac, this may result a little strange -and of course slower- but I find it very cool and useful because you can do everything you need using only one keyboard and one mouse). This will allow you to take full advantage of the machine that still runs "inside" your secondary monitor (e.g. media server for your home)

hope this helps

ciao,
m
 
Last edited:

theluggage

macrumors 603
Jul 29, 2011
5,262
4,340
According to this page thunderbolt 3->2 adapter + thunderbolt 2 cable does not support DisplayPort video, despite having the same connector. Can anyone confirm if is this true?

Pretty sure that what that means is that

Mac ---> TB3 cable ---> TB3/2 Adapter ---> MiniDP cable ---> DisplayPort Display
or
Mac ---> TB3 cable ---> TB3/2 Adapter ---> MiniDP-to-VGA/DVI/HDMI adapter --> VGA/DVI/HDMI Display

Won't work, but

Mac ---> TB3 cable ---> TB3/2 Adapter ---> TB1/2 cable ---> TB2 Dock/Drive ---> DisplayPort device
or
Mac ---> TB3 cable ---> TB3/2 Adapter ---> TB1/2 cable --> Thunderbolt Display
or
Mac ---> TB3 cable ---> TB3/2 Adapter ---> TB1/2 cable --> 2011 or later iMac in TDM

...should work.

Essentially, a <= 2010 iMac in TDM works as a DisplayPort display but a 2011 iMac works as a Thunderbolt display.
 

marcolin

macrumors newbie
Oct 9, 2013
15
1
Milan, Italy
I currently have a 2011 27" iMac, and I've just ordered a 2017 27" iMac (the 3.8GHz version with 580/8GB vram).
I'd like to use the older iMac as an external display for the new one. As far as I can tell from reading around, I can do this (ie both computers are capable of doing it), but need the following:

1. A Thunderbolt 3 (USB C) to Thunderbolt 2 adapter
2. A Thunderbolt cable

TIA.

Hi brookter1,

I don't know if you have already discovered by yourself but I can confirm you for sure that
Thunderbolt 3 (USB C) to Thunderbolt 2 adapter + Thunderbolt 2 cable
is working fine on my brand new iMac 5k 2017 (iMac late 2012 as target display)

ciao,
m
 

brookter1

macrumors regular
Original poster
Aug 5, 2015
108
77
Thanks Marco -- the new one came on Thursday and it's set up nicely next to the old one, which is now a file server and second screen. It works very well, so far.

I now am permanently reminded in stereo vision that the Labrador wants feeding... The difference between the 2011 screen and the new one is obvious...

Screenshot 2017-12-04 17.51.55.png
 
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