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sounds like it was a bad DP cable, the HDMI cable was good so worked.
IDK may be worth getin a new DP cable DP 1.4, there's lots of 'fake' ones out there
IDK may be worth getin a new DP cable DP 1.4, there's lots of 'fake' ones out there
I'm having the exact same problem but with an LG 49WL95C display connected to a Mac Pro 2013 6,1 (Trashcan) with D700s running Catalina - the DisplayPort 1.2 (supposedly) cable will not work unless forced to 3840x1080 (Low resolution). The default for the DisplayPort cable forces it to produce the unreadable screen shared by the OP. Using HDMI results in the 3840 resolution being automatically selected - go figure.
Oddly when I put the Mac into 5120x1440 mode and capture a screen shot it's "correct" (see second screen shot) - so whatever the problem is seems to be downstream of what the windowing system is presenting to the graphics driver.
My concern is that I am not 100% certain that I am getting the pixels I paid for - oddly the screen is being detected as a 5120x1440 screen (see attached) but I'm not confident that I'm getting as much screen real-estate as I was expecting.
To verify this I put the monitor in PBP Mode (picture by picture) whereby you can effectively treat the display as two seperate monitors with one getting its signal from DP and the other from HDMI, much as one of the other posters did.
As expected the menu bar, fonts, dock etc were all rescaled and the whole dimply felt "larger" (maybe my imagination.
Having heard that this was a Catalina specific problem I tested the same thing with my Late-2015 MBPR with AMD GPU tuning Mojave and sure enough, the problem presented in the same way as the nMP - HDMI good, DP bad. So Catalina is not the core issue AFAIK.
In desperation I tried both SwitchResX and ResXtreme and neither were able to allow me to use the screen in native 5120x1440 mode leading me to conclude that - umm, it's time for a beer.
The obvious next step is to plug in a PC or MBP with Bootcamp and see if the same DisplayPort cable works at least enabling me to eliminate that as the absolute problem.
Best of luck to everyone, a solution (or explanation) would be helpful to many.
[automerge]1578993462[/automerge]
Forgot to add the system profile for Graphics/Display which shows that the screen is being used at the lower res as you would expect (and oddly 30 bit colour)
Oddly when I put the Mac into 5120x1440 mode and capture a screen shot it's "correct" (see second screen shot) - so whatever the problem is seems to be downstream of what the windowing system is presenting to the graphics driver.
My concern is that I am not 100% certain that I am getting the pixels I paid for - oddly the screen is being detected as a 5120x1440 screen (see attached) but I'm not confident that I'm getting as much screen real-estate as I was expecting.
To verify this I put the monitor in PBP Mode (picture by picture) whereby you can effectively treat the display as two seperate monitors with one getting its signal from DP and the other from HDMI, much as one of the other posters did.
As expected the menu bar, fonts, dock etc were all rescaled and the whole dimply felt "larger" (maybe my imagination.
Having heard that this was a Catalina specific problem I tested the same thing with my Late-2015 MBPR with AMD GPU tuning Mojave and sure enough, the problem presented in the same way as the nMP - HDMI good, DP bad. So Catalina is not the core issue AFAIK.
In desperation I tried both SwitchResX and ResXtreme and neither were able to allow me to use the screen in native 5120x1440 mode leading me to conclude that - umm, it's time for a beer.
The obvious next step is to plug in a PC or MBP with Bootcamp and see if the same DisplayPort cable works at least enabling me to eliminate that as the absolute problem.
Best of luck to everyone, a solution (or explanation) would be helpful to many.
[automerge]1578993462[/automerge]
Forgot to add the system profile for Graphics/Display which shows that the screen is being used at the lower res as you would expect (and oddly 30 bit colour)
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Exactly the same visible distortion on my 5210x1440 LG - the only way it seems to work is when in double-width 1080p mode - very much first-world problem status but also not what I was hoping for - Putting the screen into Side-by-side mode (or PBP as LG calls it) works great at full res, but you wind up with a funky menu bar situation which isn't ideal and of course doesn't help with FCPX timelines for example.
Did you try using the DP cable with the display forced to 3840x1080? You will need to go into System Preferences and hold down Option when clicking on Scaled and then also enable show low resolutions and then select the 3840x1080 (Low Resolution) option.
I'd love to know if that works - and then I'd love to know how we can get our full 1440 experience!
I have a Iilama 34 inch wide screen with resolution of 3440x1440
the original DP cable I used would only show that resolution at 30Hz
I remember buying a higher spec DP cable from Amazon an it fixed the problem.
However i used Switch resX to enable HiDpi mode and set the resolution to 1720x720 because I'm getting old and its better for my eyes.
Also you might try force RGB https://www.mathewinkson.com/2013/0...ix-the-picture-quality-of-an-external-monitor
the original DP cable I used would only show that resolution at 30Hz
I remember buying a higher spec DP cable from Amazon an it fixed the problem.
However i used Switch resX to enable HiDpi mode and set the resolution to 1720x720 because I'm getting old and its better for my eyes.
Also you might try force RGB https://www.mathewinkson.com/2013/0...ix-the-picture-quality-of-an-external-monitor
Thanks @krakman - I have purchased two additional cables - one Mini DisplayPort to DisplayPort and a mDP to HDMI to treat both of them. I have good news and bad.
The bad - none of them fixed the problem.
The good - as one of the other readers observed, when using DP and HDMI in "side by side" mode you get different colour rendering which makes the whole thing seem pretty clunky. The great news is that with two mDP to HDMI cables the whole screen renders great and with Mission Control set to uncheck the "Display have seperate Spaces" it largely acts as one large display at 5120x1440 display
The "so so" part is that of course the menu bar is never where you think it's going to be, "full screen" apps get confused and the dock is going to want to do it's own thing too.
Still hoping to find a more complete solution, until then it's a good thing LG had the foresight to include Picture-by-Picture mode!
Just for extra fun I decided to use SwitchResX to force the second display in PbP mode to 5120x1440 and check this out - it would appear that it's more than capable of driving the second display to that level and the LG appears to be scaling it to fit which has me totally stumped as to what the problem actually is....
If I'm a betting man, this implies to me it's a single vs. multiple stream thing (SST vs MST) - I could be wrong...
Apple or LG (not sure who to blame here, but I have a feeling it's Apple) - get your **** together, please....
The bad - none of them fixed the problem.
The good - as one of the other readers observed, when using DP and HDMI in "side by side" mode you get different colour rendering which makes the whole thing seem pretty clunky. The great news is that with two mDP to HDMI cables the whole screen renders great and with Mission Control set to uncheck the "Display have seperate Spaces" it largely acts as one large display at 5120x1440 display
The "so so" part is that of course the menu bar is never where you think it's going to be, "full screen" apps get confused and the dock is going to want to do it's own thing too.
Still hoping to find a more complete solution, until then it's a good thing LG had the foresight to include Picture-by-Picture mode!
Just for extra fun I decided to use SwitchResX to force the second display in PbP mode to 5120x1440 and check this out - it would appear that it's more than capable of driving the second display to that level and the LG appears to be scaling it to fit which has me totally stumped as to what the problem actually is....
If I'm a betting man, this implies to me it's a single vs. multiple stream thing (SST vs MST) - I could be wrong...
Apple or LG (not sure who to blame here, but I have a feeling it's Apple) - get your **** together, please....