Dell U4919DW / MacBook pro 5k issue

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!

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!

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.

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.

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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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.

So I've just purchased the Moshi USB-C to DisplayPort on the advice of this thread .... only to find it's EXACTLY the same with no difference. Still only getting 3840 x 1080.

I'm now waiting on an Apple Chat Support to see if they can help!

Spoke to the advisor on the chat and after asking me to try all the troubleshooting procedures that I've already been through ... I've now had to schedule a call for tomorrow so a senior advisor can remote in and take a look.

I'll update again at that point as this is getting silly now.

I am having the exact same issue as well - I am running a late 2016 13" MacBook Pro with the U4919DW. I initially tried USB-C, then after reading this thread just bought the Moshi USB-C to Displayport cable from the Apple Store - but am still getting the scaled 3840x1080 resolution as the maximum.

I have tried to play around with SwitchResX but cannot find a setting or a custom resolution that will make it work.

I did notice that if you go into the monitor menu and change the aspect ratio to 1:1, the clarity and resolution greatly improves, but it takes down the scale so the image only shows on about 75% of the monitor.

I called Dell Support but they directed me to Apple Support instead.

Very much looking forward to hearing what the senior advisor has to say!

Quick update FWIW:

This morning, I tried booting into my Windows 10 side of my late 2016 MBP via Bootcamp. I was pleasantly surprised that the monitor displayed the correct resolution without any scaling! (It looked incredible!)

This leads me to believe it is a Mac OS issue and not a Mac hardware or cable-specific issue...

So, the plot thickens.

Senior Apple tech looked, took logs, tried several things and no use.

On another note, I plugged my 2018 Mac Mini into another Dell Monitor .... U2515 via HDMI and it showed 2560 x 1440

This is the first time I have seen 1440 being produced from my Mac Mini!! So now I'm suspecting that after all these different cables and ideas, the actual monitor may be at fault? I've submitted a ticket to Dell now about this as they were closed when I tried to call.

I'm hoping that this is a simple firmware update or otherwise this monitor will have to go back!

So I've also contacted Dell support and after going backwards and forwards with the usual troubleshooting procedures, this was their response :

I totally understand your concern, however, please be advised that the resolution will still depend on the system where your monitor is connected to. The monitor is still working as designed as it shows that the Mac mini's maximum resolution is 4096x2160 at 60Hz. In addition to that the monitor has its own resolution, your Mac mini and the monitor will meet half way for the screen resolution output.

But then again, at least for my late 2016 MBP 13", this seems to suggest that it should be able to do it with just one cable: https://9to5mac.com/2016/11/17/macbook-pro-external-display-requirements-4k-5k-a dapters/

I am not sure if this has been mentioned in this discussion before.

Apple takes every display's reported EDID information quite literally, and uses it to allow/disallow resolution setting from the Mac.

Dell on the other hand, has a history of using "any old EDID information that may be remotely related" and putting it into a new display's ROM, and calling it a day. Since most Dell users are using Windows, the Windows drivers simply assert the resolution in the Driver (overriding the capabilities reported by the Display) and charge ahead -- even if those settings might damage their display.

Mac Users have responded for some other Dell displays by reading out and interpreting the Dell profiles reported, then creating corrected profiles, and using the torturous Mac process of installing them manually (they are, unfortunately, inside the System Integrity Protection areas on the Mac).