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Question: Dell U4919DW / MacBook pro 5k issue

Hi,


I have just purchased the Dell U4919DW monitor to use with my early 2018 MacBook Pro 13", but unfortunately I cannot choose full resolution 5120x1440 in the settings, max is 3840x1080. I have tried the app SwitchResX to manually set the 5k resolution without luck, only scaled.


From this link I read about my MacBook before purchasing the screen that:

"this model supports a maximum resolution up to 4096x2304 at 60 Hz at millions of colors on two external displays or a single external display at a maximum resolution up to 5120x2880 at 60 Hz at over a billion colors via Thunderbolt 3 (USB-C)."

MacBook Pro "Core i5" 3.1 13" Touch/Mid-2017 Specs (Mid-2017 13" (Touch Bar), MPXV2LL/A*, MacBookPro14,2, A1706, 3163): …


My MacBook Pro has 4 USB-C ports, I'm using the left ones which operate at full speed (right ones are reduced).


Why can't I get full 5k resolution? Is it an issue with the MacBook, the connection, the screen or perhaps an iOS issue?


Additional links with information on the screen:

https://www.dell.com/support/article/dk/da/dkdhs1/sln314416/dell-u4919dw-system- requirements-and-supported-configuration…

https://www.dell.com/support/article/us/en/19/sln314339/dell-u4919dw-monitor-usa ge-and-troubleshooting-guide?lang=en#Usi…

https://www.dell.com/en-us/shop/dell-ultrasharp-49-curved-monitor-u4919dw/apd/21 0-arnw/monitors-monitor-accessories

MacBook Pro TouchBar and Touch ID, iOS 12.1

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I wonder if you have to turn off the Mac's native display. Did you try that? It may only be able to do the higher resolution if it's the only display.

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Nov 26, 2018 11:08 PM in response to kanonendk In response to kanonendk

I too have this dilemma but instead with my 2018 Mac Mini.


I'm currently using the bundled USB-C cable and I'm only seeing 3840 x 1080


I've since ordered a Thunderbolt 3 cable and will test this out when it arrives (26.11.2018) and update back on here again. I'm hoping it will give me full resolution!

Question marked as Helpful

Nov 26, 2018 11:08 PM in response to kanonendk In response to kanonendk

So, the Thunderbolt to Thunderbolt cable didn't work .... in fact nothing displayed on the monitor at all!


I suspect that as the monitor only supports USB-C and not Thunderbolt 3 - it didn't detect the signal from the Mac.


I'm waiting on a Thunderbolt 3 to DisplayPort cable to arrive this evening too, I suspect this will finally solve the issue so I will update again once that arrives!

Question marked as Helpful

Jun 12, 2019 3:37 PM in response to kanonendk In response to kanonendk

I also just got my Dell U4919 DW and having the same issues as described here.


First of all, if you are using the cables provided with the display you should absolutely be able to get the full resolution on supported Mac's (e.g. I've a 2016 MBP 13"). I validated this by installing Windows 10 in BootCamp and I was able to select the full 5120*1440. Looks like Windows somehow get the full resolution from the display channel or does have a plug & play driver in place - idk. macOS Catalina beta 1 also doesn't seem to fix the issue.




I did some analysis on that issue and probably found the root cause:


Displays communicate with the client by sending an EDID (Extended Display Identification Data). This 128 byte long data contains all informations about the display, like manufacturer, serial number, supported "standard" resolution and the native resolution.




The EDID of the U4919DW (and likely all other displays with resolutions greater than 4096 pixels ) contains 3840*1080 as the native resolution. Thats not a fault by the manufacturer but a limit of the EDID standard. The data field which contains the native resolution is 8 bytes in length for native high and width of the display. Therefore there are 4 bytes for high and 4 bytes for width which leaves us with a max value of 4096 (8^4).




Since apple already supports a variety of displays with resolutions higher than 4096, there must already be a technical solution for these displays, right?


It turns out, there is - its called "display overrides". 


Display overrides are placed in /System/Library/Displays/Contents/Resources/Overrides (SIP Protected Folder)




With way over 300 display override files, Apple actively using this technology to modify EDID's to get "problematic" displays to work correctly.


Just overriding the EDID (which would be easy since those files just contains the VendorID, ProductID and the "custom" EDID) won't work in this case because the EDID data field is to small for the value. 




Apple seems to have an additional technology for this case called "overlay" which are defined in .mtdd files which are also located at the path mentioned above. It looks like they even use .mtdd files for the LG 5k Ultrafine displays. 




Unfortunately I was not able to find any documentation for the mtdd overlay value (seems to be 384 bytes long).


Therefore we now know the root cause and the theoretical solution.




Maybe there is someone out there which knows how the overlay value in the mtdd files is calculated?


I also did open a Radar bug report providing vendor, displayid and the EDID of my U4919DW. 


As a fix might be implemented very easy, hopefully Apple will implement this soon.

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Nov 24, 2018 5:17 AM in response to kanonendk In response to kanonendk

I've been following this post, waiting to hear whether anyone has an answer. I'd like to purchase the monitor (it's on sale today), and was wondering whether you've been able to resolve the problem on your own, or if it's just not going to be compatible with a Mac. Any updates?

Nov 24, 2018 5:17 AM

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Nov 24, 2018 7:09 AM in response to marino389 In response to marino389

I always close the lid, which guess turns of the built-in display?


I will however try these first 2 procedures Monday when I return to my office:

3 Ways to Turn Off The Screen of Your MacBook Without Closing The Lid [OS X Tips] | Cult of Mac

Nov 24, 2018 7:09 AM

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Nov 24, 2018 9:52 AM in response to kanonendk In response to kanonendk

There is no requirement to turn off the internal display. The hardware for the Internal and the Hardware for the External are completely separate.


The fundamental problem is likely the adapter you are using. Most adapters will not work for this case at full resolution. This one appears to do the job, and is cheaper than most that almost work:



Moshi USB-C to DisplayPort Cable --$49.95


.

Nov 24, 2018 9:52 AM

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Question marked as Helpful

Nov 26, 2018 11:08 PM in response to kanonendk In response to kanonendk

I too have this dilemma but instead with my 2018 Mac Mini.


I'm currently using the bundled USB-C cable and I'm only seeing 3840 x 1080


I've since ordered a Thunderbolt 3 cable and will test this out when it arrives (26.11.2018) and update back on here again. I'm hoping it will give me full resolution!

Nov 26, 2018 11:08 PM

Reply Helpful (2)
Question marked as Helpful

Nov 26, 2018 11:08 PM in response to kanonendk In response to kanonendk

So, the Thunderbolt to Thunderbolt cable didn't work .... in fact nothing displayed on the monitor at all!


I suspect that as the monitor only supports USB-C and not Thunderbolt 3 - it didn't detect the signal from the Mac.


I'm waiting on a Thunderbolt 3 to DisplayPort cable to arrive this evening too, I suspect this will finally solve the issue so I will update again once that arrives!

Nov 26, 2018 11:08 PM

Reply Helpful (1)

Nov 27, 2018 8:10 AM in response to MrADeveci In response to MrADeveci

The fundamental problem is likely the adapter you are using. Most adapters will not work for this case at full resolution. This one appears to do the job, and is cheaper than most that almost work:



Moshi USB-C to DisplayPort Cable --$49.95


.

Nov 27, 2018 8:10 AM

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Nov 27, 2018 8:43 AM in response to Grant Bennet-Alder In response to Grant Bennet-Alder

According to this website, every connection type should produce full resolution with the exception of HDMI 1.4...


User uploaded file


Odd that nothing is working. Someone marked this thread as "Resolved." Since it hasn't been resolved, we might benefit from "Unresolving" it. Might generate more discussion from the community.


Also curious to know whether it is an Apple problem or a Dell problem. I talked to both and they said that it "should" work. Has anyone called Apple or Dell support and had them walk through step-by-step?

Nov 27, 2018 8:43 AM

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Nov 27, 2018 9:04 AM in response to marino389 In response to marino389

I have seen ads for many such adapters that claim the adapter supports up to "4K" 3840 by 2160.


Only the Mooshi adapter above seems store support more. There many be others, but they are few and far between.

Nov 27, 2018 9:04 AM

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Nov 27, 2018 9:07 AM in response to Grant Bennet-Alder In response to Grant Bennet-Alder

But shouldn't the USB-C cable that comes with the monitor, or the USB-C cable that came with the MacBook Pro be sufficient? Seems odd that you would need an adapter when you can plug right into the monitor directly with their own supplied cable.

Nov 27, 2018 9:07 AM

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Nov 27, 2018 9:17 AM in response to marino389 In response to marino389

according to Dell's information, the USB-C input is the "poor cousin" of the other inputs:

Input Connectors

2 x HDMI 2.0 (HDCP 2.2) (10-bit color @ 60Hz)
1 x DP 1.4 (HDCP 2.2) (10-bit color @ 60Hz)
5 x USB 3.0 Downstream port
2 x USB 3.0 Upstream port
1 x USB Type-C (Alternate mode with DP1.4, Power Delivery, and USB2.0) (8-bit color @ 60Hz)

note, for example it supports 8-bit color while the other inputs support 10 bit color.


Dell UltraSharp 49 Curved Monitor: U4919DW | Dell United States

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Nov 27, 2018 9:17 AM

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Nov 27, 2018 10:03 AM in response to Grant Bennet-Alder In response to Grant Bennet-Alder

Odd. My monitor hasn't arrived yet, so I'll have to wait to troubleshoot. If anyone else tries that Moshi cable, let us know if it solves the problem.


It kinda defeats the purpose of the USB-C though, having power and data through a single cable.

Nov 27, 2018 10:03 AM

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Question: Dell U4919DW / MacBook pro 5k issue