Target Display Mode to return?

[bluespark]

no, i believe we are both correct. the first imacs with target display allowed just about anything to input into them. but when TB came along, that changed and only macs can output to TDM. see here:

https://www.tekrevue.com/tip/ins-outs-imacs-target-display-mode/

Ah, okay. My hope is that these new iMacs will do what my much older one could, but we'll see. Thanks for the clarification.

 

[kelvin_chan]

As I found out that the TDM will not be enabled in the 2017 iMacs, I am trying to look for other solutions...

Not sure if you guys have already tried to do the Screen Sharing via Thunderbolt Cable instead of Wifi...

It seems more stable, not too laggy while sharing.. Do you guys have any inputs on this?

 

[jlokanis2]

Wait, does it work or does it not? One post above said it worked at the Apple store. Another says they tried it at home and it does not.
Does it work only with the latest MBP?
If you have tried it, please reply with the configuration you used and if it was successful.

 

[ZMacintosh]

I'm curious if 2017 27-inch iMac to 2017 27-inch iMac will work. would be great to use one as a secondary processing device/server/additional display/etc and get rid of the 2016 15-inch tbMBP+LG Displays

 

[tanwh]

My small work desk can only fit one monitor.

I use Mac for personal stuff and Windows for work. Virtualization and boot camp are less ideal compared with a Windows PC connected to iMac via TDM.

Hoping that TDM is enabled for iMac 2017 or iMac Pro.

 

[kelvin_chan]

Wait, does it work or does it not? One post above said it worked at the Apple store. Another says they tried it at home and it does not.
Does it work only with the latest MBP?
If you have tried it, please reply with the configuration you used and if it was successful.

I used my 2015 15" MacBook Pro Retina to try, no luck.

https://discussions.apple.com/thread/7976201?start=0&tstart=0

People are saying the Apple Store Support confirmed 2017 iMac does not support TDM

 

[redheeler]

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.

You must have a Mid 2010 27" iMac as I do. Starting with the 2011, you MUST have Thunderbolt for Target Display Mode to work. This renders Target Display Mode unusable for: nearly all Windows PCs (there may be some with Thunderbolt), all pre-2011 Macs, all pre-2013 Mac Pros, and all external GPUs.

Does it work only with the latest MBP?

If there is any sort of Target Display Mode on the 2017 iMac, the answer to this will very likely be YES. Meaning the feature is useless unless you have a 2016 or 2017 MacBook Pro, another 2017 iMac / iMac Pro, or a future-release Mac with Thunderbolt 3.

 

[tanwh]

Does it work for Windows PC with Thumderbolt 3 graphics card?

 

[bluespark]

You must have a Mid 2010 27" iMac as I do. Starting with the 2011, you MUST have Thunderbolt for Target Display Mode to work. This renders Target Display Mode unusable for: nearly all Windows PCs (there may be some with Thunderbolt), all pre-2011 Macs, all pre-2013 Mac Pros, and all external GPUs.

Much to my surprise, I checked and you are correct -- my iMac is a mid-2010. I bought it in late 2011, but I had forgotten that I bought this particular computer through the refurb store. The limitation you describe is concerning, as I need to be able to use my iMac as a display for my work laptop, which runs Windows. It works beautifully on the 2010 iMac, but that computer otherwise needs to go. Fingers crossed that the new ones support this, but now I'm worried.

 

[rkuo]

I used my 2015 15" MacBook Pro Retina to try, no luck.

https://discussions.apple.com/thread/7976201?start=0&tstart=0

People are saying the Apple Store Support confirmed 2017 iMac does not support TDM

It is not possible for you to have tested with a 2015 MacBook Pro.

 

[theluggage]

There are no tricks with TB3 and 5K ... dual displayport 1.2 streams are part of the spec. The new iMac already has TB3 built in, the question is whether Apple bothered to wire everything up.

The question is, whether the internal panel in the 5k iMac can be driven by dual DisplayPort 1.2 streams.

The old 1440p iMacs had display panels that were, single-stream displayPort devices - switching from the iMac's internal displayPort to an incoming displayPort stream from the thunderbolt or displayport socket would have been fairly trivial to implement.

Since DisplayPort 1.2 can't actually support 5k on a single stream, the 5k iMacs, instead, used a custom, high speed interface to drive the panels at 5k so it would need significant extra circuitry to convert an incoming dual-stream DisplayPort signal from TB3 to drive the panel.

I've never seen a report on whether the iMac 5k display panel is working in multi-stream (i.e. driven as two separate displays as required by DP1.2) or single-stream device (i.e. a "true" 5k panel - possible with a custom interface), If it's the latter, then it's just plain not compatible with TB3 or DisplayPort 1.3 without major hardware processing.

Few things are impossible, but TDM would be far harder to implement on the 5k.

 

[MadDane]

Is there any news from people who have received their 2017 iMac's and tested with a 2016/2017 MBP? As many others I am curious about this since I have had a use for it in more than one occasion with my current iMac

 

[rkuo]

I just tried a 2016 MacBook Pro against the new 21.5 inch iMac and target display mode did NOT work. If that didn't work, I think the chances of TDM working on the iMac 27 are essentially zero.

 

[havenyoung]

I just tried a 2016 MacBook Pro against the new 21.5 inch iMac and target display mode did NOT work. If that didn't work, I think the chances of TDM working on the iMac 27 are essentially zero.

Did you use a Thunderbolt 3 cable?

 

[Takuro]

Did you use a Thunderbolt 3 cable?

+1 if you look at the post from the person who claimed to get it to work, its very finicky and requires a full bandwidth TB3 port. If you're using a 13", remember it has some ports that don't run at full speed due to constraints.

Per Apple's documentation:

"MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports) supports Thunderbolt 3 at full performance using the two left-hand ports. The two right-hand ports deliver Thunderbolt 3 functionality, but have reduced PCI Express bandwidth."
​

Ref:
https://support.apple.com/en-us/HT207256

Original post from person claiming it works. The statements seem to be in line with the above support doc too.

yep, 5k imac can act as a display. (tested in apple store) You need a tb3 cable that connects to a 15" MBP to the current imacs, or if you have the 13" you need to connect to 1 from the left side, the 2 tb3 from the right are not working

 

[ZMacintosh]

Just tried at the Apple Store with the Thunderbolt 3 cable from the LG UltraFine 5K display with two iMacs together with no luck, and tried with. 2016 tbMBP 13" with no success either, although it does charge the tbMBP while plugged into the iMac

 

[MadDane]

Just tried at the Apple Store with the Thunderbolt 3 cable from the LG UltraFine 5K display with two iMacs together with no luck, and tried with. 2016 tbMBP 13" with no success either, although it does charge the tbMBP while plugged into the iMac

Thanks for the feedback. That's a bummer.

 

[Precursor]

Just tried at the Apple Store with the Thunderbolt 3 cable from the LG UltraFine 5K display with two iMacs together with no luck, and tried with. 2016 tbMBP 13" with no success either, although it does charge the tbMBP while plugged into the iMac

Were those iMacs 2017 model or 2016? Big difference

 

[MadDane]

Were those iMacs 2017 model or 2016? Big difference

The 2015 model (there is no 2016) does not have Thunderbolt 3/USB-C. So the cable ZMacintosh said he used (TB3 from LG Ultrafine) would physically not fit in anything other than the 2017 model of the iMac.

 

[Precursor]

The 2015 model (there is no 2016) does not have Thunderbolt 3/USB-C. So the cable ZMacintosh said he used (TB3 from LG Ultrafine) would physically not fit in anything other than the 2017 model of the iMac.

My bad, that's true
So there's contradicting info from posters here. One user said he tested at Apple store and it worked, one other says it didn't.
Guess we'll find out when these iMacs start getting delivered.

 

[ZMacintosh]

Were those iMacs 2017 model or 2016? Big difference

Yes, brand new 2017 27-inch iMacs using TB3.

 

[bunnicula]

Hmm... I guess Apple will have to wow me another year, then. More money saved. My spouse will be pleased.

 

[jinnyman]

Very disappointing.. Since TDM is no longer limited by technology, I would suspect that Apple's made a strategic choice to disagle TDM so that the product shall be replaced more often. Typical Apple.

 

[morphodone]

According to an iMore article it was a technical issue and some of the blame is on Intel.
https://www.google.com/amp/s/www.imore.com/imac?amp

It affects features too. iMacs used to support target display mode so they could be used as a monitor for other Macs. Now they don't. That's because Intel kept delaying the integration of 5K-capable DisplayPort — and continues to delay it — and so Apple had to make 5K work without Intel and, in so doing, had to sacrifice Target Display mode.

 

[Takuro]

Oh well, that's that then. Still very confusing why one person claimed it worked where-as we now have at least a few people independently confirming it does not work.

According to an iMore article it was a technical issue and some of the blame is on Intel.
https://www.google.com/amp/s/www.imore.com/imac?amp

Thunderbolt 3 supports dual Displayport 1.2 streams, as somebody pointed out in the first page of this thread. Although it's true that Displayport 1.2 maxes out at 4k, by sending two streams to a single monitor, each can effectively drive 1/2 of the pixels to "stitch together" one 5k picture.

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.