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At the end of the day the question could be simplified to "if you can use an LG 5K display with a Mac over a single TB3 cable today, why can't you use an iMac in target display mode similarly?" I think at best all anybody can do is hypothesize a guess.

We can do better than that. :)

This is a clear sign that Apple is still using the custom timing controller chip they developed for the original iMac 4K and iMac 5K to allow it to run the display at 60Hz. It works, so why change it?

To make TDM work with TB3 would require Apple to re-engineer that timing controller and TDM would then only work with other Macs that have TB3. I am sure it was deemed not worth the effort since so few people probably did it when it was available years ago.
 
This is a clear sign that Apple is still using the custom timing controller chip they developed for the original iMac 4K and iMac 5K to allow it to run the display at 60Hz. It works, so why change it?
I was thinking the same thing. When they first announced the 5K iMac, they spent quite a bit of time focusing on their timing chip and how proprietary it was since no industry standard solutions existed. I'm not sure what the LG 5K monitor does, but it achieves a 60 Hz refresh rate. I assumed since Apple worked with LG on it, they'd found a better solution to drive a 5K display so it could be used over Thunderbolt and that this would in turn eventually make its way to the iMac. I guess not?

We'll see what happens. 2018 is apparently going to see a physical refresh of the iMac's enclosure, and there's sure to be some substantial hardware changes internally too.
 
I'm not sure what the LG 5K monitor does, but it achieves a 60 Hz refresh rate.

Thunderbolt 3 supports two DisplayPort 1.2 streams over a single cable so the LG display is using one DP1.2 stream to draw the left half of the panel at 60Hz and one DP1.2 stream to draw the right half of the panel at 60Hz. Kind of like how Dual-Link DVI allowed one to use a 30" LCD display (each DVI link drove one half of the panel).
 
That's not correct. I routinely use my 2011 as a "dumb monitor" for a Windows PC with a mini display port. Of course, I have no idea whether the new iMacs will do this.

I also have a 2011 iMac and would like to use it as Target Display Mode, what cable do you use from your PC to your iMac?

Thanks
 
I also have a 2011 iMac and would like to use it as Target Display Mode, what cable do you use from your PC to your iMac?

Thanks

Should be able to use a mini-displayport or DisplayPort to mini-Displayport cable
 
Should be able to use a mini-displayport or DisplayPort to mini-Displayport cable
Thanks for your response.

Is your iMac a 2011 one? Mine is and an adapter from display port (from PC) to mini display port (to iMac) won't work. Cable is fine btw as I tested it from a Macbook pro to Dell screen.

I just need the same functionality from my iMac as you described above so thanks in advance.
 
Thanks for your response.

Is your iMac a 2011 one? Mine is and an adapter from display port (from PC) to mini display port (to iMac) won't work. Cable is fine btw as I tested it from a Macbook pro to Dell screen.

I just need the same functionality from my iMac as you described above so thanks in advance.

If you iMac is in fact mid-2011 with Thunderbolt it will not work unless your PC has thunderbolt connectivity.
I believe the other use has a 2009 or 2010 iMac and they perhaps are mistaken on what version it is.

Apple:
https://support.apple.com/en-us/HT204592



They have an older iMac, this will not work for them.
 
Apple support, both phone and chat, told me that TDM is back with the iMac Pro. Neither could point me to anything written however. $5k is pretty steep to get TDM, but I can't work without it.
 
Apple support, both phone and chat, told me that TDM is back with the iMac Pro. Neither could point me to anything written however. $5k is pretty steep to get TDM, but I can't work without it.

I'm glad, if it's true. Maybe this means it'll be back on the regular iMac next time around.
 
Apple support, both phone and chat, told me that TDM is back with the iMac Pro. Neither could point me to anything written however. $5k is pretty steep to get TDM, but I can't work without it.

Color me skeptical, given that Target Display Mode hasn't been built into products for so long that would Apple Support staff be even trained to know what it is?

But the optimistic part of my brain wants to believe, so I'll go Mulder over Scully for now!

I assume if it did come back it would be a purely Thunderbolt 3 to Thunderbolt 3 play.

I'd really like to be able to have a (custom built) PC show its image on the iMac Pro screen from time to time. It could possibly be done with something like this: https://www.gigabyte.com/Motherboard/GC-ALPINE-RIDGE-rev-10#ov
 
I was advised by Apple support that you can use the Thunderbolt 3 to Thunderbolt adapter and use target display on another iMac...provided it is thunderbolt technology. According to the support person, he checked with someone higher up (he could be feeding me a line, but that doesn't sound like Apple to me) and confirmed the 2017 iMac does allow for target display....just make sure the target display is thunderbolt!

With that, I will need to retire my 2009 iMac. Been using it in target display with my 2012 iMac utilizing the thunderbolt port, and the miniDisplayPort on my 2009 iMac. It's been a good run, first iMac. Time to go to that Apple Store in Boca.
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Did that work for you? I use target display mode on my 2010 iMac and can’t see myself getting a new iMac if it does not support target display mode.
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will the target display mode on new iMac's work with older laptops which only have Display Port, or even Windows system with Display Port?
Your laptops, whatever brand, will need to have Thunderbolt 3 to connect to a new 2017 iMac. The old 2010 iMac 27 with a Mini DisplayPort connection can connect to any laptop with Thunderbolt or mini DisplayPort connection.
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I just got my new iMac and seems target display mode doesn't work for me....trying to update the software and see what happens....
Any word? Did it eventually work on 2017 iMac?
 
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Your laptops, whatever brand, will need to have Thunderbolt 3 to connect to a new 2017 iMac. The old 2010 iMac 27 with a Mini DisplayPort connection can connect to any laptop with Thunderbolt or mini DisplayPort connection.
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Any word? Did it eventually work on 2017 iMac?
As mentioned, Target Display Mode does not work on 2017 iMacs.
 
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