NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
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Have two LG 27" 4k displays working with a Macbook Pro.

All was working fine under Mojave.

Now on Catalina, the second display is no longer as sharp as the first display.

Furthermore, when going to SETTINGS -> DISPLAYS I can scale down Display #1 but Display #2 doesn't have the same scaling option with the little box selections.

I take it this is a bug in Catlina? Do you think it will be fixed?
 

alien3dx

macrumors 68000
Feb 12, 2017
1,781
389
Have two LG 27" 4k displays working with a Macbook Pro.

All was working fine under Mojave.

Now on Catalina, the second display is no longer as sharp as the first display.

Furthermore, when going to SETTINGS -> DISPLAYS I can scale down Display #1 but Display #2 doesn't have the same scaling option with the little box selections.

I take it this is a bug in Catlina? Do you think it will be fixed?
No for my baseline 2017 imac + samsung 21 + sidecar .3 monitor lol
 

Lucky736

macrumors 6502a
Jan 18, 2004
910
533
US
My LG 4k 21.5 has all sorts of refresh rate issues now. Not sure what is going on, tried adjusting everything.....
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
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My LG 4k 21.5 has all sorts of refresh rate issues now. Not sure what is going on, tried adjusting everything.....

Thanks for letting me know. It seems like a bug that is going to have to be worked out through an update.
 
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MaryQ

macrumors newbie
Dec 12, 2019
5
0
Have two LG 27" 4k displays working with a Macbook Pro.

All was working fine under Mojave.

Now on Catalina, the second display is no longer as sharp as the first display.

Furthermore, when going to SETTINGS -> DISPLAYS I can scale down Display #1 but Display #2 doesn't have the same scaling option with the little box selections.

I take it this is a bug in Catlina? Do you think it will be fixed?

I just bought 2 new LG 4k monitors and I am seeing the same behavior. I also note that the second monitor is showing a 30 Hertz refresh rate and resolution of 1920x1080 - yuck! I didn't have the monitors before I upgraded to Catalina, so I can't tell you if it would have worked before the upgrade. Have you had any luck by changing any settings? I am considering returning the monitors at this point.
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
I just bought 2 new LG 4k monitors and I am seeing the same behavior. I also note that the second monitor is showing a 30 Hertz refresh rate and resolution of 1920x1080 - yuck! I didn't have the monitors before I upgraded to Catalina, so I can't tell you if it would have worked before the upgrade. Have you had any luck by changing any settings? I am considering returning the monitors at this point.


My issue is that I really know squat about resolutions.

The best I have been able to get is 2560x1440 (60Hz)
Under Mac OS X settings ->Display, the monitors are scaled 2nd selection from the left (larger to smaller)

I also put both displays in HDREffect (LG Monitor settings)

The monitors look good. Could be a little sharper.

Try those settings. Let me know if you can do any better
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
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Perhaps someone who knows, let US know what resolution is best for 27" monitor RETINA
 

MaryQ

macrumors newbie
Dec 12, 2019
5
0
None here. I have dual 27 inch Apple Cinema Display's at home and an iMac in target disk mode and a Dell monitor at work.
Can you send me a link to the exact monitor you have? It's not too late for me to return the LG monitors and if you are having success I would want to consider the monitors that are working for you. I would definitely want 2 external monitors, and 27" is a good size. Thanks!
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
Can you send me a link to the exact monitor you have? It's not too late for me to return the LG monitors and if you are having success I would want to consider the monitors that are working for you. I would definitely want 2 external monitors, and 27" is a good size. Thanks!


It sounds like he has the Apple Displays. I thought there were only two: the old ones from a few years back and the new Pro displays that just came out this week.
 

MaryQ

macrumors newbie
Dec 12, 2019
5
0
It sounds like he has the Apple Displays. I thought there were only two: the old ones from a few years back and the new Pro displays that just came out this week.
Are you referring to the LG Ultrafine displays on apple.com? Has anyone tried them? They look awesome but are really expensive.
 

tommiy

macrumors 6502
Dec 11, 2015
331
108
Yes I have a LG 27UK850 that works perfectly with Mojave 10.14.5 but catalina some times gets the rsolution incorrect and I need to unplug it and replug back in. Eventual Catalina gets it right. Most of the external display problems for me started with 10.14.6 and after a few discussions with Apple engineers they agreed that there was problems in .6 and to wait for catalina. Now catalina fixed the problems i had with .6 but introduced 3 new ones which you can find on the apple communities. Seems each release simply breaks something else. Next release that completely works I'll stop upgrading at because I'm tired of having a year between working and maybe working...
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
Yes I have a LG 27UK850 that works perfectly with Mojave 10.14.5 but catalina some times gets the rsolution incorrect and I need to unplug it and replug back in. Eventual Catalina gets it right. Most of the external display problems for me started with 10.14.6 and after a few discussions with Apple engineers they agreed that there was problems in .6 and to wait for catalina. Now catalina fixed the problems i had with .6 but introduced 3 new ones which you can find on the apple communities. Seems each release simply breaks something else. Next release that completely works I'll stop upgrading at because I'm tired of having a year between working and maybe working...


Can you post your most optimal resolution on those 27" monitors so we can try to match them?

Include the scaled setting in OS X DISPLAYS

Thank You
 

chrono1081

macrumors 604
Jan 26, 2008
7,786
2,252
Isla Nublar
Can you send me a link to the exact monitor you have? It's not too late for me to return the LG monitors and if you are having success I would want to consider the monitors that are working for you. I would definitely want 2 external monitors, and 27" is a good size. Thanks!
Sadly they don’t make the ones I have anymore. They’re the cinema displays that came out in 2010.
 

tommiy

macrumors 6502
Dec 11, 2015
331
108
I'm not exactly sure what you mean by 'optimal resolution" however the scaled resolution is 2560x1440. Of curse to find this I had to turn my MAC on which resulted in the retina display going full brightness and needing manual intervention to get it back to normal as Catalina is broken there as well. See link below.

Here is my issue with 10.14.6. Essentially Apple broke nightshift with external monitors resulting in the kernel trying to change the resolution every 5-10ms. Windows Server goes 40% CPU load.

10.14.6 External Monitor Windows Server High CPU Load

And here is the continuation issues across into 10.15.1 which should have the information you are looking for.
Catalina gets resolution wrong when HDMI switching external monitor
Catalina Screen brightness issue with external monitors
Catalina polling external monitors when asleep
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I'll try 10.15.2 on the weekend but I've got used to now needing many hours to be invested in minor dot releases by Apple. The time consumed means that it does not just work like it used to. The very next release that works I stop upgrading because the unreliability of Apple is just a roller coaster when it comes to trying to use a MAC with external monitors...either that or I return to High sierra which did not have visible problems with external monitors.
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
When it comes to sizing up your picture on a 27" monitor you have so many options.

There are different levels of scaling if you go into settings -> Displays

If you use something like ResX, EasyRes or any software that lets you do additional tinkering, you have dozens of choices.

I guess my question is which setting/resolution gives you the most razor-sharp images for the monitor?
 

tommiy

macrumors 6502
Dec 11, 2015
331
108
Spent last 3hrs trying to convince my MAC to upgrade to 10.15.2. Seems to get to about 9 minutes left to go and sits and does nothing. Left it for an hour in this state and zip. Start back up and recovery and reinstall 10.15.1. I think I'm bordering on giving in on Apple. The experience is now worse than windows.
[automerge]1576231984[/automerge]
Seems like I finally got it to upgrade...not the way I would have liked....literally had to turn it off va the power button during the upgrade and then it recontinued. Looking at the logs it appeared that the WindowServer crashed during the upgrade and this appears to stop it from proceeding..... well, after that and finally after 3.5hrs I can say these problems still exist.

Catalina Screen brightness issue with external monitors
Catalina gets resolution wrong when HDMI switching external monitor

The 3rd I need to wait until deep sleep but seeing the lack of success on the others I guess it will still be present as well. Time to roll back after that. 10.15.2 a bust for me rather stay with .1 and the issues it has than move towards more apple issues.
 
Last edited:

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
Again, if anyone can take a moment..

What settings are you running the monitors at? Include the scaled setting in Max OS X

Thanks
 

tommiy

macrumors 6502
Dec 11, 2015
331
108
I run a elgato thunderbolt 3 dock with an old Apple Cinema Thunderbolt2 monitor and the LG 27uk850. The UK 850 I scale to 3840x2160 @60Hz on a HDMI active adapter.
 

NJRonbo

macrumors 68030
Original poster
Jan 10, 2007
2,661
563
I run a elgato thunderbolt 3 dock with an old Apple Cinema Thunderbolt2 monitor and the LG 27uk850. The UK 850 I scale to 3840x2160 @60Hz on a HDMI active adapter.


Thank You! The first person who actually posts their resolution settings although it has been asked many times in this thread. Very much appreciate that.
 

tommiy

macrumors 6502
Dec 11, 2015
331
108
No problems. Note that Catalina is unreliable on detecting the monitor properly. Mojave had no issues at all. I can work all day effectively at that resolution but if the MAC goes to sleep then it will wake up and have the uk850 in a mode where i can not scale and the display app simply does not offer scaling. I unplug the MAC from the dock for 30 sec and plug it back in and then it comes back with scaling options. Mojave never behaved in this manner its a Catalina bug....along with the other 3 HDMI related Catalina bugs.
 
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