Dell U4919DW / MacBook pro 5k issue

Hi Apexkingjusto,

I just buy the Philips 499P9H, and the new MBP 15" 2018, to work at home. For me it was the perfect combination.

The dock fonction (ethernet, webcam, usb) on the screen work perfectly with the usb-c. But I have the same problem with the resolution who stay in 3840*1080 instead of 5120*1440.

I hope that Apple fix this problem with the next update 10.14.4....

I just tried this one but no luck. The only thing I get is two displays on the Philips side by side each with a resolution of 3840 x 1080 according to systempreferences. Only resolutions with a ratio of 32:9 are display which means I can't set the output of USB-C or USB-C to HDMI to 2560x1440.

Mac Mini 2018 and Dell monitor. I've just upgraded and I can't get 5120x1440 working, PBP still works.

Side note, the more I use PBP the more I like it. Two discreet displays without the bezel in the middle is working 'seamlessly' for me (see what I did there).

Are you sure that it is an upscaled version? It looks quite good on my screen. I tested the PBP as well but I didn't see any 16:9 resolution as a dropdown option in the system preferences. When choosing 2560x1440 in SwitchResX, which is the only possibility, the image looks almost identical to the (upscaled) version of 5120x1440.

When I choose a lower resolution than 5120x1440 in SwitchResX or system preferences my monitor warns me that I'm using a low resolution. There is no warning when choosing 5120x1440 from SwitchResX.

I'm unsure what you mean. The issue for me was the fact that when using the full 5120x1440 with SwitchResX on my Mac mini the resolution of the whole image would be scrambled like it was upscaled and sharpened, when selecting 5120x1440 on my old MacPro (which does have dedicated graphics but not the right ports) it would scramble the image even more, shifting the pixels in layers to make an even more scrambled video. the highest resolution both Macs would allow me without the (low resolution) tag was 1080p.

So I guess my solution of using external graphics only really makes sense if SwitchResX does not help the issue. As to the PBP situation, I also run two screens at 2560x1440 from both of those computers with no issue, so I don't think you would even need SwitchRes for that.

I do wonder how you got 5120x1440x70hz working then yanickfromebnat-kappel. That’s even higher then what JeanLuc7 is saying.

I cannot go higher then 5120x1440x30hz without using third party apps or hacks. And only in clamshell mode.

You are right JeanLuc7

It's only a limitation of macOs.

A shame that you must install a windows OS on a Apple computer to reach the full resolution of a display.

Time where Apple make me dream is far away...

10.14.5 brings no change - still the monitor can be operated on the mini only in the split mode as two virtual displays with 2560x1440. After all, 2560x1440 is now offered as a "scaled" resolution (and also correctly implemented) - that was not so at the beginning (with 10.14.3), as far as I remember.

If you want to connect more than one machine, you are able to do so. For example, you can connect the Mini with two cables (USB-C and DP) using PBP and connect the MBP using HDMI. Within the monitor menu, you can select which signals will be used for PBP, so you may have one of the Mini's displays on one side and the MBP on the other. You should keep in mind that using PBP also means switching off the Mission Control function "Monitors use different spaces" (otherwise windows will be cut off in the middle of the monitor if they are not completely visible on the left or the right side). In this case, the Mini will show only one menu bar, and it may be a good idea for the MBP monitor side to select the display side without the Mini's menu bar.

DisplayPort is a more advanced protocol than "legacy" display protocols. A DisplayPort-capable display has its own display buffer, and only the changes are sent across the cable.

There is no 60Hz "heartbeat" refresh (required for CRT displays) so the refresh rate can be much quicker. But sometimes the reported rate is actually from the display's internal display offer to its screen.

Interesting. So I can expect possibly 120hz as well? I have a new Mac mini and the U4919DW. I have been doing the PBP “solution” with USB-C to DP and HDMI. It’s a great monitor but I am looking forward to a real solution.

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.

I also just bought this monitor and can report the same issue. Resolution is capped to 3840x1080, even though the technical specs for my 2018 MacBook Pro states that it can support up to 5120x2880 on an external monitor. Very deceiving...

As Leo found out in the post above, there is probably a simple fix that Apple can apply to support this monitor. Hopefully they are listening and if enough people complain they will do something about it

Hi Ontemay112, I have a Mac mini and the Philips 499p9h that uses the same panel I believe. I have tried switchresX but none of the configurations I try work. It always complains that the configuration is invalid. Would you mind sharing your switchresx settings?

Hey Leo971,

first thank you for your detailed analysis. I've also looked into the EDID before and came to the same conclusion but didn't have the time & patience to try and "hack" a new one myself.

I'm also having the Philips 499P and not the Dell, but as I know most 32:9 use the same Samsung panel anyway. I've also dumped the EDID from a Linux pc to avoid the Intel driver mangling it but also this didn't lead to a solution yet.

I'm close to returning the display but if you you need any support let me know. Seeing that other people are also actively looking for real solutions gives me hope instead of those just advising people stupid solutions like using multiple adapters + PBP ... .