Connecting an Intel iMac to a M1Pro...is that possible?

[coolbreeze2]

I have an iMac (see my siggy). The tech specs list the following:

• Two Thunderbolt 3 (USB-C) ports with support for:
• DisplayPort
• Thunderbolt (up to 40 Gbps)
• USB 3.1 Gen 2 (up to 10 Gbps)
• Thunderbolt 2, HDMI, DVI, and VGA supported using adapters (sold separately)

I have the new M1Pro 14 inch. The tech specs list the following:

• HDMI port
• Three Thunderbolt 4 (USB-C) ports with support for:
• DisplayPort
• Thunderbolt 4 (up to 40Gb/s)
• USB 4 (up to 40Gb/s)

I want to connect the two with the M1Pro as the primary machine to use the 27 inch 5K monitor of the iMac as the screen for the M1Pro. I want to be able to drag a window of an application from the M1Pro to the iMac and work within that window. Is that possible? I am able to do this with M1Pro and my iPad 3rd generation (not old but 2 generations behind the new models). I was thinking that if works with an iPad, it should work with iMac that's about the same age as the iMac. Will it work with the iMac? What's the best way?

Thanks!!!!

UPDATE: I called Apple support and the rep said this is possible with iMacs from 2009-2014 and with the 2020 iMac. However iMacs in between 2014 and 2020 will not allow this. That's crazy that an old 2009 iMac will work but not a newer 2017. Yet one as new as a 2020 will work. I'm thinking this is Apple's "official" response but my 2017 will actually work. I just need to figure out the "unsupported" method.

 

[Fishrrman]

Is your iMac a "5k" model?
They can't do "target display mode", to my knowledge.

I don't think Monterey still supports target display mode, in any case.
I could be wrong, hopefully others will correct me.

 

[coolbreeze2]

Is your iMac a "5k" model?
They can't do "target display mode", to my knowledge.

I don't think Monterey still supports target display mode, in any case.
I could be wrong, hopefully others will correct me.

Yes my iMac is 5K. So that's the issue, the 5K screen. Who would have thought a better monitor is the problem. Is there a possible unsupported method?

 

[ponzicoinbro]

Thunderbolt Bridge Network

 

[coolbreeze2]

Thunderbolt Bridge Network

Ok so all I need to to do is connect to the two via Thunderbolt 3 and configure the connection under Network in System Preferences? Or do I need some kind of hardware and/or software?

 

[ponzicoinbro]

Ok so all I need to to do is connect to the two via Thunderbolt 3 and configure the connection under Network in System Preferences? Or do I need some kind of hardware and/or software?

Use IP over Thunderbolt to connect Mac computers

Connect two Mac computers together using Thunderbolt and set them up to communicate with each other using Internet Protocol (IP).

support.apple.com

Little tweaking.

 

[CWallace]

UPDATE: I called Apple support and the rep said this is possible with iMacs from 2009-2014 and with the 2020 iMac. However iMacs in between 2014 and 2020 will not allow this. That's crazy that an old 2009 iMac will work but not a newer 2017. Yet one as new as a 2020 will work. I'm thinking this is Apple's "official" response but my 2017 will actually work. I just need to figure out the "unsupported" method.

The iMac 4K and 5K ended Target Display Mode support because they use a custom timing controller to allow the display to be refreshed at 60Hz and this does not support TDM. As the 2020 iMac is also a 5K it also does not support Target Display Mode.

I presume the Apple Support tech was referring to the ability under macOS Monterey for recent Macs to use another Mac as a display and this does work with the 2019 and 2020 iMacs - https://www.macrumors.com/2021/06/09/airplay-mac-to-mac-external-display/

 

[coolbreeze2]

The iMac 4K and 5K ended Target Display Mode support because they use a custom timing controller to allow the display to be refreshed at 60Hz and this does not support TDM. As the 2020 iMac is also a 5K it also does not support Target Display Mode.

I presume the Apple Support tech was referring to the ability under macOS Monterey for recent Macs to use another Mac as a display and this does work with the 2019 and 2020 iMacs - https://www.macrumors.com/2021/06/09/airplay-mac-to-mac-external-display/

Ok thanks for the information. It helped me to understand.

 

[coolbreeze2]

Use IP over Thunderbolt to connect Mac computers

Connect two Mac computers together using Thunderbolt and set them up to communicate with each other using Internet Protocol (IP).

support.apple.com

Little tweaking.

Ok I am going to try this as soon as finish something I am working on. I might have questions and will post them.

 

[coolbreeze2]

Use IP over Thunderbolt to connect Mac computers

Connect two Mac computers together using Thunderbolt and set them up to communicate with each other using Internet Protocol (IP).

support.apple.com

Little tweaking.

Ok I am going to try this as soon as finish something I am working on. I might have questions and will post them.

Ok these are the instructions on the page you linked me to:

• Connect a Thunderbolt cable to the Thunderbolt ports on the computers you want to connect.
• On your Mac, choose Apple menu
  
  > System Preferences, then click Network
  
  .
  
  
• Select Thunderbolt Bridge in the list on the left.
• Click Advanced, click DNS, then enter the DNS and search domain addresses if your network requires them. Check with the network administrator or your ISP if you’re not sure what the addresses are.
• Click OK, then click Apply.

The 2nd bullet: Which Mac? I want the windows applications from the MacBook to show on the iMac.
Do I need to go into the Preferences of both or only one machine?

 

[coolbreeze2]

Ok these are the instructions on the page you linked me to:

• Connect a Thunderbolt cable to the Thunderbolt ports on the computers you want to connect.
• On your Mac, choose Apple menu
  
  > System Preferences, then click Network
  
  .
  
  
• Select Thunderbolt Bridge in the list on the left.
• Click Advanced, click DNS, then enter the DNS and search domain addresses if your network requires them. Check with the network administrator or your ISP if you’re not sure what the addresses are.
• Click OK, then click Apply.

The 2nd bullet: Which Mac? I want the windows applications from the MacBook to show on the iMac.
Do I need to go into the Preferences of both or only one machine?

Ok I got it to work!!! Thanks!! To be sure and its just not my imagination, after connecting, on the iMac I opened Paralles. It opened and ran and I can see it on the iMac screen.!! Parallels is not installed on my iMac but it's installed on my MBP M1/Pro. I am now going to try some other apps just be sure because I did have Paralles installed on my iMac earlier this year. I uninstalled it but somehow could still be there.

 

[carl varley]

Screen sharing is a good alternative to Target Display Mode. It can work really well. I use my iMac 2011 as a second screen for my M1 mac mini with a ethernet cable as a local network between the M1 Mini and iMac and a cheap 4k headless HDMI adapter from amazon with really great results. This allows the GPU to be used for screen acceleration.

 

[coolbreeze2]

Ok I got it to work!!! Thanks!! To be sure and its just not my imagination, after connecting, on the iMac I opened Paralles. It opened and ran and I can see it on the iMac screen.!! Parallels is not installed on my iMac but it's installed on my MBP M1/Pro. I am now going to try some other apps just be sure because I did have Paralles installed on my iMac earlier this year. I uninstalled it but somehow could still be there.

Ok not all apps are working. I'll try the screen sharing suggestion above.

 

[Juicy Box]

I called Apple support and the rep said this is possible with iMacs from 2009-2014

It might be important to note that not all 2009-2014 iMacs do Target Display Mode, and the 2020 iMac doesn't do TDM as far as I know.

Plus, even with 2009-2014 iMacs that are TDM capable, only the 2009-2010 models can be used with M1 Macs.


To clarify, Late 2009 to Mid 2010 27" iMacs are capable of Target Display Mode via the Mini DisplayPort, and can be used as a monitor to the M1 Mac, or just about any other device that can output via Display Port.

Mid 2011 to Late 2013 21" and 27" iMacs are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

Mid 2014 21" iMacs are the latest that are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

It is also important to note that the "Target" iMac needs to have a supported OS to be used as a monitor. I think the highest support OS is 10.13. I recall seeing people claiming that they got TDM working with Mojave, but I never have tried it.

That's crazy that an old 2009 iMac will work but not a newer 2017.

It is worse than that, only the 2009 and 2010 iMacs will work with your M1 using Target Display Mode. Not the TB ones.



There are some alternatives, such as Screen Sharing and third party options, but none of them are as good as Target Display Mode.

I use Screen Sharing daily, with all my Macs. I usually do it just to control my various Macs remotely, but some are headless. The problem with Screen Sharing is the lag. Even with a 1Gbps Ethernet connection, there is still some lag. There is a setting in screen sharing to adjust the quality versus speed, to improve the experience based on what is important to you:


Adaptive Quality with give you the smoothest performance, but degraded. Full Quality will be more laggy and stutters, but looks better.

Third party options might be better for what you want. While I have never used it Luna Display seems to be popular:

Luna Display — by Astropad

The only hardware solution that turns any Mac or iPad into a wireless second display.

astropad.com

 

[coolbreeze2]

It might be important to note that not all 2009-2014 iMacs do Target Display Mode, and the 2020 iMac doesn't do TDM as far as I know.

Plus, even with 2009-2014 iMacs that are TDM capable, only the 2009-2010 models can be used with M1 Macs.


To clarify, Late 2009 to Mid 2010 27" iMacs are capable of Target Display Mode via the Mini DisplayPort, and can be used as a monitor to the M1 Mac, or just about any other device that can output via Display Port.

Mid 2011 to Late 2013 21" and 27" iMacs are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

Mid 2014 21" iMacs are the latest that are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

It is also important to note that the "Target" iMac needs to have a supported OS to be used as a monitor. I think the highest support OS is 10.13. I recall seeing people claiming that they got TDM working with Mojave, but I never have tried it.


It is worse than that, only the 2009 and 2010 iMacs will work with your M1 using Target Display Mode. Not the TB ones.



There are some alternatives, such as Screen Sharing and third party options, but none of them are as good as Target Display Mode.

I use Screen Sharing daily, with all my Macs. I usually do it just to control my various Macs remotely, but some are headless. The problem with Screen Sharing is the lag. Even with a 1Gbps Ethernet connection, there is still some lag. There is a setting in screen sharing to adjust the quality versus speed, to improve the experience based on what is important to you:
View attachment 1904196

Adaptive Quality with give you the smoothest performance, but degraded. Full Quality will be more laggy and stutters, but looks better.

Third party options might be better for what you want. While I have never used it Luna Display seems to be popular:

Luna Display — by Astropad

The only hardware solution that turns any Mac or iPad into a wireless second display.

astropad.com

This is some awesome information!!!! I just tried screen sharing. I used Full Quality and experienced no lag or stutter. However, I didn't do anything intensive. I am considering Luna Display as you suggested. The price is $129. That's a little tight on my budget right now considering I just purchased my M1 Pro and Apple Care+. However it's a lot more affordable than buying a new display to pair with my M1. I just hate that I can't re-purpose my 27 inch iMac as a monitor for my new MBP M1 Pro.

 

[carl varley]

I use a dummy 4k HDMI headless adapter. like this one:

EZDIY-FAB HDMI Dummy Plug,Headless Ghost, Display Emulator, Supports 4K 3840x2160 60Hz-1Pack

It fixes a problem you probably didn't even know you had - unlocking the full potential of your graphics card hardware. By simulating the presence of an attached display, display emulator allows you to use all of the power and available resolutions locked away inside your graphics hard...

www.amazon.co.uk

This lets you use the second display in different resolutions with graphics acceleration the same principle as Luna display. This gives a smother frame rate (around 25-35fps @ 1440p for me with 1Gbs ethernet cable). Using thunderbolt as a a network cable gets the frame rate up a bit more too but I've not been able to get the 60fps that the iMac would display native. I always turn wifi off before connecting as it will sometimes connect via that with sluggish results.

Screen sharing also has the benefit of having the shared mac in a window or in fullscreen shared keyboard and mouse, shared clipboard and drag and drop between computers. Its really good and built in for free. Hope that helps!

 

[coolbreeze2]

I use a dummy 4k HDMI headless adapter. like this one:

EZDIY-FAB HDMI Dummy Plug,Headless Ghost, Display Emulator, Supports 4K 3840x2160 60Hz-1Pack

It fixes a problem you probably didn't even know you had - unlocking the full potential of your graphics card hardware. By simulating the presence of an attached display, display emulator allows you to use all of the power and available resolutions locked away inside your graphics hard...

www.amazon.co.uk

This lets you use the second display in different resolutions with graphics acceleration the same principle as Luna display. This gives a smother frame rate (around 25-35fps @ 1440p for me with 1Gbs ethernet cable). Using thunderbolt as a a network cable gets the frame rate up a bit more too but I've not been able to get the 60fps that the iMac would display native. I always turn wifi off before connecting as it will sometimes connect via that with sluggish results.

Screen sharing also has the benefit of having the shared mac in a window or in fullscreen shared keyboard and mouse, shared clipboard and drag and drop between computers. Its really good and built in for free. Hope that helps!

Thanks for this information. I didn't know this existed. This is all new to me. So, please be patient with me. Do you plug the dummy in the MBP? or the iMac? or both?

 

[carl varley]

Thanks for this information. I didn't know this existed. This is all new to me. So, please be patient with me. Do you plug the dummy in the MBP? or the iMac? or both?

You plug it into your MB Pro. I think you can get a USB C version too.

 

[coolbreeze2]

You plug it into your MB Pro. I think you can get a USB C version too.

Ok thanks

 

[coolbreeze2]

I use a dummy 4k HDMI headless adapter. like this one:

EZDIY-FAB HDMI Dummy Plug,Headless Ghost, Display Emulator, Supports 4K 3840x2160 60Hz-1Pack

It fixes a problem you probably didn't even know you had - unlocking the full potential of your graphics card hardware. By simulating the presence of an attached display, display emulator allows you to use all of the power and available resolutions locked away inside your graphics hard...

www.amazon.co.uk

This lets you use the second display in different resolutions with graphics acceleration the same principle as Luna display. This gives a smother frame rate (around 25-35fps @ 1440p for me with 1Gbs ethernet cable). Using thunderbolt as a a network cable gets the frame rate up a bit more too but I've not been able to get the 60fps that the iMac would display native. I always turn wifi off before connecting as it will sometimes connect via that with sluggish results.

Screen sharing also has the benefit of having the shared mac in a window or in fullscreen shared keyboard and mouse, shared clipboard and drag and drop between computers. Its really good and built in for free. Hope that helps!

Ok I ordered one and it will be here in 3 days. Thanks again.

 

[coolbreeze2]

It might be important to note that not all 2009-2014 iMacs do Target Display Mode, and the 2020 iMac doesn't do TDM as far as I know.

Plus, even with 2009-2014 iMacs that are TDM capable, only the 2009-2010 models can be used with M1 Macs.


To clarify, Late 2009 to Mid 2010 27" iMacs are capable of Target Display Mode via the Mini DisplayPort, and can be used as a monitor to the M1 Mac, or just about any other device that can output via Display Port.

Mid 2011 to Late 2013 21" and 27" iMacs are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

Mid 2014 21" iMacs are the latest that are capable of Target Display Mode via Thunderbolt. This will not work with M1 Macs.

It is also important to note that the "Target" iMac needs to have a supported OS to be used as a monitor. I think the highest support OS is 10.13. I recall seeing people claiming that they got TDM working with Mojave, but I never have tried it.


It is worse than that, only the 2009 and 2010 iMacs will work with your M1 using Target Display Mode. Not the TB ones.



There are some alternatives, such as Screen Sharing and third party options, but none of them are as good as Target Display Mode.

I use Screen Sharing daily, with all my Macs. I usually do it just to control my various Macs remotely, but some are headless. The problem with Screen Sharing is the lag. Even with a 1Gbps Ethernet connection, there is still some lag. There is a setting in screen sharing to adjust the quality versus speed, to improve the experience based on what is important to you:
View attachment 1904196

Adaptive Quality with give you the smoothest performance, but degraded. Full Quality will be more laggy and stutters, but looks better.

Third party options might be better for what you want. While I have never used it Luna Display seems to be popular:

Luna Display — by Astropad

The only hardware solution that turns any Mac or iPad into a wireless second display.

astropad.com

Ok I have tried screen sharing using Wifi and tried with Thunderbolt Bridge. I selected Full quality with both and TB bridge was very acceptable! Now I am waiting for the headless adapter to arrive. I think the combination of it and the bridge will be awesome.

 

[carl varley]

Hope it works out for you. I'm not sure how very high resolutions work such as 4k and 5k. If you find the screen size too small or fps too low you can alway lower the resolution of your iMac. Holding down alt whilst clicking Scaled will then show actual resolutions including low res mode.


As mentioned I use it with my iMac 2011 which is 1440p and works brilliantly for using as a second screen, copying files between computers and using two computers in a single screen.

 

[coolbreeze2]

Hope it works out for you. I'm not sure how very high resolutions work such as 4k and 5k. If you find the screen size too small or fps too low you can alway lower the resolution of your iMac. Holding down alt whilst clicking Scaled will then show actual resolutions including low res mode.


As mentioned I use it with my iMac 2011 which is 1440p and works brilliantly for using as a second screen, copying files between computers and using two computers in a single screen.

Ok thanks!