MBPr 2015, 2.5GHz i7 – Daisychaining 2 Dell U2414H 61 Screens

Question

Marking this question as an already existing question is wrong as the other question refers to a Mid 2012 NONretina Macbook running 10.10.1 instead of 10.10.3/4

I think that daisy chaining DisplayPort screens under OS X 10.10.4 is not possible, due to software limitations defined by Apple.

After Googling for some hours, spending 1.5 hours talking to the Apple Support and another hour talking to the Dell support, I don't know where else to find a solution than here.

This is my problem:

I just bought a new MacBook Pro Retina 2015 2.5GHz i7, 16GB RAM, NVIDIA GeForce 750M running OS X Yosemite 10.10.3.

I have two Dell U2414H 24" screens.

I want to use one of my two Thunderbolt/DisplayPort ports from my MacBook to connect both screens via a daisy chain. (I know that I could easily plug each screen into its own Thunderbolt/DisplayPort. But I need to use one Thunderbolt/DisplayPort for my Ethernet adapter, so I only have one left.)

So the setup I'm trying to run looks like the following:

MacBook --(from mDP to DP)--> Screen 1 --(from DP to mDP)--> Screen 2

However, whenever I connect the cables like this, I only receive the same image on both screens, i.e. the image is mirrored to both screens.

I don't understand why this is the case. If I connect the same setup to a Windows machine, it is working fine. While Googling I found some articles which say that "a Mac running Windows will daisy chain monitors".

Both screens support DisplayPort 1.2 as well as MST ("DisplayPort 1.2 added support for Multi-Stream Transport (MST), enabling multiple monitors to be used via a single DisplayPort connector.") and I enabled Display Port 1.2 on both screens within the menu.

So, as Windows machines and a MacBook running Windows support this setup, I concluded that it has something to do with OS X running. I tried to download the newest drivers for my graphic card form Nvidia. However, I learned that Apple provides the drivers, not Nvidia (“Nvidia drivers are provided by Apple and they are updated with every OS X maintenance update.”).

So I think that Apple is intentionally restricting the usage of Display Port 1.2 with non-Apple screens by limiting this function within the drivers.

Can this be true?

Does anybody have a solution for this problem, or know what to do?

I tried to find open source drivers for my graphic card and my MacBook which would enable this function, or maybe some hacked drivers, but had no luck yet.

Update 1: 3 June 2015

After Googling again for some hours, I decided to test the statement (link above) that a MacBook running Windows is able to daisychain. I installed Windows 8.1 on my MacBook via Bootcamp.

When running Windows 8.1 with the actual Nvidia drivers, daisychaining multiple displays through one Thunderbolt port is possible.

So I conclude that Apple is intentionally limiting the capabilities of OS X, to force customers to buy their Thunderbolt displays if they want functionality that should be possible with normal displays, and breaking the official standards.

I contacted the Apple Support again, and met a very competent and helpful supporter, who deep-dived into my problem. He escalated the problem to the European technology department of Apple, questioning why daisychaining display port monitors is not possible on OS X.

I am still waiting for a response from the department, but this can take up to 5 days, according to the supporter.

If I get any answer, I'll post it here.

Update 2: 6 June 2015

Today my Apple support rep gave me a call to inform me that he received a response from the European technology department of Apple. However, the department only referred to a support article of Apple and quoted the following "[...] as each Thunderbolt port can support one Mini DisplayPort display." Therefore, they could only speculate why daisychaining does not work but decided to not do so as it wouldn't help.

My support then told that this answer is not very satisfying and asked for further help.

It seems like this daisychaining problem is either not known at Apple and therefore not solved (maybe we can make Apple pay attention by spamming the developers with the form mentioned below), or Apple does not want to solve the problem in order to force customers to buy the more expensive Apple Thunderbolt Display.

I am keeping this thread up to date for other people searching the web for the same problem.

If you are experiencing the same problem, then please fill out Apple's feedback form and tell the developers to change the macOS behaviour regarding daisychaining.

http://en.community.dell.com/support-forums/peripherals/f/3529/t/19347208.aspx
The first line from that page sets the stage for all of the Dell-Apple monitor issues outlined thereafter: "We do not validate our monitors with any apple proprietary hardware or software." — dennismuijs, Jun 06 '15 at 13:59
@dennismuys - Yes thanks for your comment. That is right, it is the same information which I received from the Dell support hotline. As Dell is not validating their monitors with any Apple products, they cannot help troubleshooting. — Robin, Jun 07 '15 at 10:35
Did you enable MST on the dell monitors in the monitor's settings menu? — , Jun 07 '15 at 12:28
@Cornhoilio – "and I enabled Display Port 1.2 on both screens within the menu." I guess that is what you refering to, isn't it? If so, yes I did enable MST on the dell monitors' menus. — Robin, Jun 07 '15 at 14:03
I had read various things about this setup not working if you chain two monitors immediately together, but working if there was another thunderbolt device between them. YMMV but I bought one of these and it solved my problem: http://amzn.to/1dnnxWe it also only worked when in the chain after the first monitor, not before. — Tom Lianza, Jun 07 '15 at 14:41
I know it's not the solution you want to hear, but how about you use two thunderbolt cables, one for each display, and then use a USB to ethernet adapter? — ktappe, Jun 07 '15 at 14:49
Questions don't necessarily have to be exactly the same to be considered as duplicates. It's primarily about pointing to the right answer. — slhck, Jun 07 '15 at 14:58
Just curious, have you tried an MST hub like this with you setup: http://www.amazon.com/StarTech-com-DisplayPort-Triple-Multi-Monitor/dp/B00JLRBC7S/ref=sr_1_1?ie=UTF8&qid=1433692570&sr=8-1&keywords=displayport+mst? — pseudosavant, Jun 07 '15 at 15:56
My solution to this issue is to daisy chain the thunderbolt ethernet adapter to one of my screens and plug the two screens to my Mac. — Christopher Chiche, Jun 07 '15 at 21:18
@ChristopherChiche – this won't work, because the displays are no thunderbolt displays but display port displays so they can't take thunderbolt devices within the chain, or am I missing anything? — Robin, Jun 09 '15 at 21:16
I can confirm under Windows 10 that both my U2414H monitors work chained from one thunderbolt port. When I boot into OS X 10.11.2 I get mirroring instead. Also according to System Inforation > Hardware > Graphics/Displays my monitor is a TV. There are "overrides" that can fix this, not sure if it will enable chaining but I doubt it. — Garrett, Jan 06 '16 at 07:24
Just to let everyone know, i tried using the beta nvidia drivers hoping there might be an off chance it would work, but alas still not daisychain... http://www.nvidia.com/download/driverResults.aspx/93555/en-us — OrangeBox, Feb 25 '16 at 04:45

score 13 · Answer 1 · answered Jun 07 '15 at 13:08

13

Apple does not support Display Port daisy chaining.

Using Thunderbolt screens, this would work, and because the Apple screen is a Thunderbolt screen, that works. The fact that Windows supports DP daisy chaining, does not mean that Apple does this intentionally to force users to buy their monitor.

So... Never attribute to malice that which is adequately explained by stupidity.

I wouldn't even call this stupidity, just ignorance, or the simple fact that nobody at Apple was aware of this situation and didn't test for it, or they did test for it and decided it wasn't worth the money.

answered Jun 07 '15 at 13:08

SPRBRN

1,230

But if Apple "was not aware of this siutation", what they do is ignoring officially defined standards as "Other improvements [of DisplayPort 1.2; added by author] include multiple independent video streams (daisy-chain connection with multiple monitors) called Multi-Stream Transport" (http://en.wikipedia.org/wiki/DisplayPort#1.2a) or? – Robin Jun 07 '15 at 14:05
Does Apple advertise full DP 1.2 compatibility? – Michel Müller Jun 08 '15 at 05:49
3

If one reads here: https://support.apple.com/en-us/HT202856 it says: "Multi-Stream Transport (MST) Displays; These computers also support multi-stream transport (MST) [...] " So it shows that the MacBooks does support DisplayPort 1.2 or MST but only for ONE Instead of MULTIPLE displays, which is against the offical standard. – Robin Jun 08 '15 at 10:32
Had to find out the same thing with 2 U2415 displays. Mirroring works, but not extending. Works under Windows though. Even better, at work I have two Cinema Displays that are daisy chained -> No Problem – Evils Sep 18 '17 at 01:29

score 4 · Answer 2 · edited Apr 13 '17 at 12:45

4

This is answered at Apple Macbook Dual Monitor MST already.

Apple is not "intentionally limiting" anything. They simply didn't add MST support to OS X because their hardware doesn't need it. The physical Mini DisplayPort connector on your Mac can operate in two modes, one is DisplayPort itself. In this mode, you can connect a single 4K 60 Hz monitor to your Mac. Or, you can use it in Thunderbolt mode where the displays use the Thunderbolt bus which has two DisplayPort signals multiplexed into the stream and each monitor gets one signal out -- but it's DP 1.1a so 4K 30 Hz or Full HD 60 Hz.

edited Apr 13 '17 at 12:45

Community

1

answered Jun 07 '15 at 13:02

chx

468

8

But doesn't this article by Apple state that the newer MacBooks do support MST: https://support.apple.com/en-us/HT202856 – Robin Jun 07 '15 at 14:01
1

As pointed out by sj26 in that question, chaining uses MST but MST support doesn't imply chaining support. Since this question is specifically about chaining, it isn't answered already by the other question. – Garrett Jan 06 '16 at 07:12
2

Thunderbolt 2 ports support Displayport 1.2 and apart of the Displayport specification is support for daisy-chaining. Apple does support MST enabled monitors with dp1.2, but still daisychaining doesnt work... seems like a convenient oversight – OrangeBox Feb 25 '16 at 04:58
2

Intentional limiting - the OS is the problem. The OP stated: "a MacBook running Windows is able to daisychain. I installed Windows 8.1 on my MacBook via Bootcamp." – Ed of the Mountain Sep 13 '17 at 17:27

MBPr 2015, 2.5GHz i7 – Daisychaining 2 Dell U2414H 61 Screens

Update 1: 3 June 2015

Update 2: 6 June 2015

2 Answers2

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