Hi KGP,
Thanks for all you do. Your guides have been very helpful.
I recently received my 2x 34wk95u-w monitors, meant to replace some good old Dell U3415WB monitors. So the intention is to go from 3440x1440@60 x2 to 5120x2160@60 x2. I had previously helped a client set up an LG ultrafine 5K monitor, so I was aware that getting resolutions above 3840x2160 could be a challenge.
First of all, the monitor's DP is definitely DP1.4. You can actually select the DP operating standard in the menu (1.4, 1.2 or 1.1)
Of course there is also a thunderbolt 3 port, but a minor frustration there is that there is no second thunderbolt 3 port so the monitor has to be an endpoint device.
From all my research and understanding of the capabilities of the various ports, one SHOULD be able to drive the monitor at full resolution via one of two methods:
1) Set the monitor to use DP 1.4 mode, and connect the monitor using a DP 1.4 certified cable to a DP 1.4 port on a supporting GPU. In my case i am running a 1080TI which does have DP 1.4 ports.
2) Connect two DP cables between the GPU and a thunderbolt 3 AIC and connect the monitor via TB3 cable (this is how i got the ultrafine 5K working for my client, that monitor ONLY has this Thunderbolt 3 port option)
I am attempting option #1. However i have yet to have success running the full resolution with macOS.
I am using the monitor supplied cable (which has a 5K label on it) to make sure cable quality should not be a factor.
I have tested with both the most recent LILU/Whatevergreen kexts, as well as the modified kexts from this thread:
https://www.tonymacx86.com/threads/nvidia-gtx1080-lg-ultrafine-5k-full-5k-60hz-success.240730/
Using the latest kexts, even with the common boot-args suggested (-ngfxnoaudio ngfxpatch=pikera nv_createDetailedTimingsFromEdid=1 -ngfxnoaudiocon -liludbgall) i seem fully restricted to 3840x2160 or bellow in macOS.
Using the modified kexts and the above boot-args, i can get macOS to select the full 5120x2160- and it recognizes the monitor and from the OS side everything seems correct and working, however the monitor remains completely blank/black. I am only able to interact with the computer via screen sharing (which again, appears at full resolution) or by having a second lower resolution monitor attached. For whatever reason whenever i send a full resolution signal, the monitor just goes blank even though it otherwise appears to be working to macOS. Switching to DP 1.2 mode on the monitor brings it back to life, albeit limited to 4K resolution max.
At this point i am scratching my head and wondering if macOS completely lacks support for DP 1.4 at this time? Or if this is an nvidia limitation? I am "stuck" at 10.13.6 because of lack of nvidia support in 10.14, but i do have a vega64 and RX580 available to test with so that might be next.
Also as a sanity check, full 5K 5120x2160 works perfectly and OOB in windows 10. So the cable seems fine and the GPU and monitor are working correctly together given the right circumstances- but i have not been able to create those circumstances in macOS.
I also have little doubt that option #2, connecting the monitor via TB3 would work, as i have gotten that to work with my client using the ultrafine 5K and the same GPU. But because these monitors are thunderbolt endpoints, and because my GPU only has a total of 3 DP ports, i will need to get at least one of the two monitors working with option #1.
Anyway, these monitors are beautiful, and i hope we can figure out a solution to nvidia + DP 1.4 for 5K over a single cable in macOS.
g\
