Can I connect old iMac to new iMac & use as additional monitor?

[Rhobes]

Hi All-
I bought a new iMac last June because my 2010 iMac started to fail. I never found out what the problem was yet it still works but with some problems. If interested in seeing those problems check here: https://forums.macrumors.com/thread...-to-imac.2184203/?post=27433056#post-27433056

Anyway, I'm thinking it possibly may work well enough to use as an additional monitor if I could connect it to my new iMac. I do video editing etc and the extra screen space would be great. I just don't know if I can connect and use it for that purpose, whether it works or not. Yet, I sure would like to try it, if possible.

So, can it be done? If possible, maybe someone in the "know" could explain how to and the connectors needed etc. Or, if there is a post somewhere on the forum that addresses this issue that would be great to see. I am including the specs on my old and new iMac below to help with any question about compatibility:

New System Specs:

2019 (June) iMac 27-inch Retina 5K Display (5120 x 2880)
3.6GHz 8-Core 9th-Gen Intel Core i9 Processor
Turbo Boost up to 5.0GHz
96 GB 2666MHz DDR4 Ram Memory
2TB SSD Storage
Radeon Pro Vega 48 GPU Graphics Card & 8 GB of HBM2 Memory

Connections:
3.5 mm Headphone jack

Four USB 3 ports (compatible with USB 2)

Two Thunderbolt 3 (USB-C) ports with support for:
DisplayPort; Thunderbolt(up to 40Gb/s); USB 3.1 Gen 2 (up to 10Gb/s);
Thunderbolt 2, HDMI, DVI, & VGA supported using adapters

10/100/1000BASE-T Gigabit Ethernet (RJ-45 connector)


========================================================================================

Old System Specs:

2010 (mid May) iMac 27”/4850-512M
Processor: 065-9233 2.8GHz Quad-Core Intel Core i7;
Memory: 065-9266 8GB 1066MHz DDR3 SDRAM-2x4GB;
Hard Drive: 065-8407 2TB Serial ATA Drive;
Display: 27- inch (2560 x 1440)
Graphics: 065-8981 ATI Radeon HD 4850 512MB
OPTICAL DRIVE 065-9410 8X DOUBLE-LAYER SUPERDRIVE
OS: 10.11.5 El Capitan

Connections:
Ethernet port (10/100/1000Base-T). Connect to a high-speed 10/100/1000Base-T Ethernet network, connect a DSL or cable modem, or connect to another computer and transfer files. The Ethernet port automatically detects other Ethernet devices.

Mini DisplayPort. Output port with support for DVI, VGA, and dual-link DVI. The 27-inch model also supports input from external DisplayPort sources. Required cables and adapters are available separately.

Four high-speed USB (Universal Serial Bus) 2.0 ports. Connect an iPod, iPhone, mouse, keyboard, printer, disk drive, digital camera, joystick, external USB modem, and more. You can also connect USB 1.1 devices.

Audio in/optical digital audio in port. Connect an external powered microphone or digital audio equipment. This port is also a S/PDIF stereo 3.5 mini-phono jack

Headphone out/optical digital audio out port. Connect headphones, external powered speakers, or digital audio equipment. This port is also a S/PDIF stereo 3.5 mini-phono jack.

FireWire 800 port. Connect high-speed external devices, such as digital video cameras and storage devices. The port provides up to 7 watts of power.

Thanks for any help with this question

 

[Juicy Box]

Yes

Target Display Mode:

Mac User Guide

Learn what’s new in macOS, how to get started with your Mac and use it with your Apple devices, and how to control privacy and security on macOS.

support.apple.com

Use TB cable to connect the two. This will require and Apple adapter for the TB3>TB2 and then a TB cable to connect the two.
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If interested in seeing those problems check here: https://forums.macrumors.com/thread...-to-imac.2184203/?post=27433056#post-27433056

I am unsure about how TDM would be affected by the issues you are having, so this might be an issue.

Those issues sound like a GPU issue, similar to one I had with a Mid-2011 27" iMac. I fixed the issue by doing a GPU bake.

I am not sure if you want to go through all that just to use your 2010 as a second monitor.

I would, but thats me.
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I ran the quick and extended versions of the Apple Hardware test, both results were: "No Trouble Found". I believe that indicates not a hardware but a software problem exists.

Apple's HW diagnostic gives false negatives a lot. That 2011 iMac I mentioned above also passed the HW diagnostic test many times, all while having graphic artifacts all over the screen.

Even the Apple Store's HW diagnostic tool gives false negatives.

I had a failing HDD in a Fusion Drive on my Late 2012 iMac, all the symptoms pointed to the drive, but Apple refused to replace it under the warranty because it passed their tests.

They wipe the drive, reinstall the OS, only for me to have the issues come back once I started using those bad sectors on the HDD, and back to the Apple Store and have it pass their HW diagnostic. Rinse and repeat...........

Luckily for me (or maybe unluckily), it totally failed 12 days before my warranty was over.

 

[Rhobes]

Target Display Mode:

Mac User Guide

Learn what’s new in macOS, how to get started with your Mac and use it with your Apple devices, and how to control privacy and security on macOS.

support.apple.com

Thanks so much for your reply Vertical smile! After looking at the link you supplied " Use your iMac as a display" I see there is a "Note" under that heading that states " Target Display Mode isn't supported on iMac models with Retina display." My new iMac would act as the primary computer in my case which has the Retina display.

But, under the 3rd heading "Use a 27" iMac with a Mini Display Port as an external display" would fit as my old iMac spec, to be used as the external display. The 1st sentence under this 3rd heading states "If you have a 27-inch iMac with a Mini DisplayPort

, any other Mac with a Mini DisplayPort or Thunderbolt port

can use it as a display. This now seems to qualify the connection between my New (Primary) with thunderbolt computer & Old (external display) with Mini DisplayPort computer iMacs. Yet, the Note from the 1st heading may override this. That note stating the Retina display will not support Target display mode. As the 3rd heading continues I see I would only need the video (more specifically just capacity to store images) without audio.

Anyway, I haven't put my new iMac on line yet. I want to load the new additional ram and transfer files etc from my old iMac to the new as yet. So, I think I'll have to wait a bit till I power it up and open the New Mac Apple menu to see ifit can actually be done. Apple says it's possible if one has TB the other Mini DisplayPort but then the "Note" from the 1st heading saying "Target Display Mode not supported with Retina displays".

Oh well, more to come-

 

[ApfelKuchen]

The "target" Mac can't have a Retina display. However, the primary (video source) Mac can have Retina. I've done exactly that (Retina iMac sending video to the non-Retina iMac - both Macs have Thunderbolt ports,).

I think the note in the support article is saying that, as long as the target iMac has Mini DisplayPort, it can be the "target" of another Mac with either a Thunderbolt or Mini DisplayPort.

 

[Juicy Box]

Just to clarify to anyone looking at this thread to TDM answers:

Any Late 2009 to Late 2013 27" iMac or Mid 2011 to Mid 2014 21" iMac can be used as an external monitor to any Mac that has a Thunderbolt port.

Any Late 2009 to Mid 2010 iMac can be used as an external display to any Mac with a Mini Display Port.



To the OP:

You have an old Mid 2010 27" iMac with a Mini Display Port which can be used as an external monitor to your Mid 2017 iMac with Thunderbolt 3. This may involve using adapters.

According to Apple: You can use a USBC to MDP adapter:

Adapters for the Thunderbolt or USB-C port on your Mac - Apple Support

Learn about different adapters for the Thunderbolt 5, Thunderbolt 4, Thunderbolt 3, or USB-C port on your Mac.

support.apple.com

Maybe someone else who has this set up can comment.

 

[theluggage]

According to Apple: You can use a USBC to MDP adapter:

...further clarification:

to connect a 2017 to a 2009-2010 iMac with Mini DisplayPort you need a USB-C to Mini DisplayPort cable (or "USB-C" to DP/MiniDP adapter + DP/MiniDP-to MiniDP cable).

to connect a 2017 to a 2011-2013 iMac with Thunderbolt you need a Thunderbolt 3 to Thunderbolt 1/2 adapter plus a Thunderbolt 1/2 cable.

...although the end result still looks like it has USB-C on one end and MiniDP on the other, they work in quite different ways.

Again, that's in theory - please correct me if you have actual experience.

All complaints about the ambiguity of the term "USB-C" to the USB IF, please

 

[Rhobes]

to connect a 2017 to a 2009-2010 iMac with Mini DisplayPort you need

To be clear, I'm trying to connect a 2019 Retina 5K iMac ( with Four USB 3 ports and TwoThunderbolt 3 ports) to a 2010 iMac (non-Retina) with Mini DisplayPort.

 

[Rhobes]

Hi everyone, I'm spending so much time looking for the cables/adapters. Thinking I found something, maybe someone could check it out in the link supplied?
https://www.apple.com/shop/product/HLR62ZM/A/moshi-usb-c-to-displayport-cable

So, this is incorrect cable. See post below!

 

[Rhobes]

Here is the answer, I got through to Apple help. One single cable, "Mophie USB-C Cable with Mini DisplayPort Connector". See here: https://www.apple.com/shop/product/...-connector?fnode=8b&fs=f=cable&fh=4595%2B45c4

As most here have suggested and in all the Apple help it continually states multiple adapters are necessary. I found a single cable (similar to that in the Apple link above) from a 3rd party vender site but they explicitly warned NOT to use it connecting two computers due to fire hazard and machine/display damage.

I attached the Apple Support Help conversation with "Connect with a Specialist". I took 4 screen shots of entire online chat.

 

[Rhobes]

I also contacted "Cable Matters" and they returned with a similar and cheaper cable see here: Amazon

I went with the above Apple option, always a better choice in the end when dealing with cables as I've learned. Included the correspondence from the company in attachment.

 

[Fourcue]

Hello:
Having carefully read the entire post, I’m sorry if it sounds dumb to ask, but did the “Mophie USB-C Cable with Mini DisplayPort Connector” that Apple Support Help recommended actually work?
I’m trying to use a late 2009 iMac 27” (with a mini-display port) as the 2nd monitor for a iMac 2021 27”(with Thunderbolt 3), so this cable sounds like exactly what I’m looking for!
Thank you.

 

[Rhobes]

Hello Fourcue-
Sorry, but I was diverted from this attempt due to relocation and job and have yet to get back to this. I expect to resume (try) this monitor hook-up in a couple months, I still haven't plugged in the new Mac at this point. I will update here if I get it to work, I'm still far behind getting anything on this done but hope to get back to it-

 

[Fourcue]

Thank you for the update. I may well proceed anyway & report back. Thanks again!

 

[A1S2M345]

This thread is a bit old, yet what i did was to try a month free usage of a program called 'Duet Display'! It surprisingly allowed me to connect my iMac 2017 to my iMac 2011 via wifi! I also had success connecting my iMac to my windows pc laptop with success for all connections. Currently its free to try for 30 days.. and after that.. less than 30.00 usd / year! So far so good, with a few quirks which I can fix from my end...

Duet - Use Your Devices As A Second Display, Drawing Tablet, Remote Desktop, And More

Be productive from anywhere - connect your devices to turn them into a lightning fast second monitor, a Remote Desktop to access from anywhere, a drawing tablet, and more.

duetdisplay.com

Let me know...