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Did you try changing DisplayPort versions in the monitor settings?
Just tried, same result.

EDIT: Read over on Reddit that when you share your display over AirPlay to an Apple TV or AirPlay capable TV, and then end the session, the issue fixes itself temporarily. This worked for me over USB-C. Gives me hope that this can be fixed in software.
 
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I have a Mac mini M1 and Dell U2720Q, and I am now able to get the RGB mode working. You need a spare Intel Mac. Here is what I did.

1. Connect the monitor with the Intel Mac.
2. Use the script https://gist.github.com/adaugherity/7435890 to generate the EDID patch on the Intel Mac. Since the script only works on Intel Macs and not M1 ones, you can only generate the file on the Intel Mac.
3. Disconnect the monitor from the Intel Mac and connect it to the M1 Mac.
4. Transfer the whole folder to the M1 Mac, and place it into /Library/Displays/Contents/Resources/Overrides directory. Create the directory if it does not exist before.
5. Go to display settings on the M1 Mac, and turn OFF HDR (this is the most important step. Turning on HDR will always output YPbPr to the Dell monitor).
6. In the Dell monitor, set colour preset mode to Standard, and set Smart HDR to DisplayHDR (if set to Disable, sometimes it won't work).
7. Restart the M1 Mac.

After restart, my monitor is showing RGB as the colour mode. Now is the most interesting part. I had to delete that override folder, otherwise the next restart my Mac mini will revert back to use YPbPr again.

8. Delete the override folder inside /Library/Displays/Contents/Resources/Overrides directory, and restart the M1 Mac again.

View attachment 1699087
Im trying to copy the generated directory into the Overrided dir but its read-only, how you overcame it?
 
Ok, I've been able to get my M1 MacBook Air to play nice with my
LG 27UK850-W. In my previous post I mentioned that by sharing my screen via AirPlay, I was able to to get my Mac to correct itself. As expected, my Mac reverted to non-RGB mode after I unplugged and plugged back in. After doing more research I went ahead and purchased Apple's non-active thunderbolt 3 cable (0.8m) and have no had any issues since. I've come to this conclusion after numerous unplugs and re-plugs over the past few days. Not sure how the AirPlay method factored into this, ultimately.
 
Ok, I've been able to get my M1 MacBook Air to play nice with my
LG 27UK850-W. In my previous post I mentioned that by sharing my screen via AirPlay, I was able to to get my Mac to correct itself. As expected, my Mac reverted to non-RGB mode after I unplugged and plugged back in. After doing more research I went ahead and purchased Apple's non-active thunderbolt 3 cable (0.8m) and have no had any issues since. I've come to this conclusion after numerous unplugs and re-plugs over the past few days. Not sure how the AirPlay method factored into this, ultimately.
You mean you have an RGB signal with the Apple cable ??
 
You mean you have an RGB signal with the Apple cable ??
Kind of. I have two of the exact same monitor (LG 27UK850-W). The tests I've been running have been on monitor #1. I used AirPlay screen mirroring on monitor #1 and then proceeded to use Apple Thunderbolt 3 cable also on monitor #1.

In order to determine the effect using AirPlay mirroring had on my setup, I unboxed identical monitor #2. Hooking this up using the same Apple Thunderbolt 3 cable, I do not get an RGB signal. I have yet to use AirPlay mirroring while hooked up to monitor #2. I'll post an update here once I've done that.
 
Filed FB8946046 through Feedback Assistant. I encourage anyone affected to also file, referencing this number.

Make sure your problematic display is connected at the time of writing the feedback so that it is present in the system profile sent to Apple.
Friendly reminder to consider this time investment to push Apple for a fix.
 
Im trying to copy the generated directory into the Overrided dir but its read-only, how you overcame it?
It should not be read-only. I just copied it to the directory in Finder. There are no special steps. But based on the posts after my original post, I think the override method was not necessary to achieve RGB display. The essential way is to 1. enable the Smart RGB in the dell monitor, and 2. Disable the HDR setting in macOS display setting. After that, restart your machine and most likely you will have the RGB mode. Also you need to use display port or USB with DP alt mode. HDMI is a hit and miss and I won't recommend it.
 
Screen Shot 2021-01-22 at 1.59.54 PM.png

Please submit a bug report via Feedback Assistant if you are on the beta or visit the Apple website if you are experiencing this issue!
 
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Hey, in case the issue is still not handled by Apple, is there any list of compatible monitors with M1 chips?
Colors are terrible on my AOC24V2Q but looks perfect on my Samsung TV (both connected with HDMI through Satechi hub). Unfortunately no chance to check if it's set as ypbpr or rgb.

 
I am about to test this same cable with my M1 Air and Dell P2721Q.

The cable is in the mailbox and I will retrieve it when my workday finishes!

Hi Adam

Hope things are going great with your new monitor! I have given up on my old monitor, and have shortlisted (in given order) to go with my M1 Macbook Air.

Dell P2721Q
Dell U2720Q
LG 27UL850-W (saw a thread elsewhere where someone is super-happy with this monitor with his M1 machine - not sure if it's ok to link here)

As you are already in possession of the first monitor, could you opine if colors are acceptable and fonts crisp with the M1 Air + P2721Q?

There is a youtube review of M1 + U2720Q where the reviewer shows OSD with YPbPr selected, right towards the end. He seems happy with the colors & fonts on it.

I also read that 11.2 might give a resolution of the YPbPr issue. Any idea is the latest beta shows this to be the case?

Thanks!
 
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Hi Adam

Hope things are going great with your new monitor! I have given up on my old monitor, and have shortlisted (in given order) to go with my M1 Macbook Air.

Dell P2721Q
Dell U2720Q
LG 27UL850-W (saw a thread elsewhere where someone is super-happy with this monitor with his M1 machine - not sure if it's ok to link here)

As you are already in possession of the first monitor, could you opine if colors are acceptable and fonts crisp with the M1 Air + P2721Q?

There is a youtube review of M1 + U2720Q where the reviewer shows OSD with YPbPr selected, right towards the end. He seems happy with the colors & fonts on it.

I also read that 11.2 might give a resolution of the YPbPr issue. Any idea is the latest beta shows this to be the case?

Thanks!
The P2721Q looks acceptable with YPbPr on the M1 Air.

Subjectively, the YPbPR color distortion is not as severe as on the U3219Q. I think this comes down to how the monitor itself handles color processing.

I bought the display mostly to use with my work MacBook Pro that outputs RGB; I'm not sure why you would buy a display with a known issue in its primary use case.

11.2 will most likely come out this week, I will be installing it of course and can report results.
 
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Thanks Adam

Basically, I don't have the ability to either demo these monitor (expensive monitors are available only on order), or return it once bought, so at some point, I will have to take a leap of faith!

I have a very strong bias towards Dell, and I will be using the same monitor interchangeably with my windows machines. So if the Dell is 95% there, I would prefer it.

Having said that, text clarity, and white balance fidelity are my No 1 and 2 priorities (so I can work with text for 8-10 hours without fatigue - I am the kind of person who can make out, if a monitor has PWM!).

On the parameter of text sharpness, is the M1 + P2721Q almost as good as your older Pro + P2721Q?

I don't mind deferring my monitor purchase by a couple of months to get it just right. I am riding on:

a) Release of Dell Display Manager for Mac (which I think Dell said was slated for Jan '21)
b) Big Sur 11.2

P.S. : I saw your comment on that youtube video :)

Cheers
 
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Hi Adam

Hope things are going great with your new monitor! I have given up on my old monitor, and have shortlisted (in given order) to go with my M1 Macbook Air.

Dell P2721Q
Dell U2720Q
LG 27UL850-W (saw a thread elsewhere where someone is super-happy with this monitor with his M1 machine - not sure if it's ok to link here)

As you are already in possession of the first monitor, could you opine if colors are acceptable and fonts crisp with the M1 Air + P2721Q?

There is a youtube review of M1 + U2720Q where the reviewer shows OSD with YPbPr selected, right towards the end. He seems happy with the colors & fonts on it.

I also read that 11.2 might give a resolution of the YPbPr issue. Any idea is the latest beta shows this to be the case?

Thanks!
I am not Adam and I do not have the Dell P2721Q, but I do have an older version of this monitor (P2715Q). I also have an old Apple Cinema Display 24" that runs at 1920 x 1200. I can confirm that the difference in text clarity between the two monitors is night and day. I would expect the newer version of the Dell monitor to work the same.

This has nothing to do with colour modes, or M1 Macs, but everything to do with MacOs itself and has been the case for many years.

I cannot comment on colours, since it's not something that is important to me.
 
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I don't have the ability to [...] return it once bought
Surprising. Are you not in the USA? Our electronics retailers have a return policy 14-30 days.

On the parameter of text sharpness
Text on Macrumors looks a bit different on the M1 compared to the Intel. Slightly worse, but hard to put my finger exactly on how. Not a big delta.

White text on a dark background looks pretty bad - e.g. Discord.

I will note that the Intel is running the latest Catalina point release, while the M1 is on Big Sur. So there could be an OS difference also.

text clarity, and white balance fidelity are my No 1 and 2 priorities
Get the LG 4K or 5K. You'll be in 2x HiDPI mode for optimal text rendering, and you'll have no YPbPr issue.
 
The P2721Q looks acceptable with YPbPr on the M1 Air.

Subjectively, the YPbPR color distortion is not as severe as on the U3219Q. I think this comes down to how the monitor itself handles color processing.

I have U3219Q and I’ve managed to get two different modes of YPbPR output from M1 mini with two different USB-C to DP adapters. With the cheaper adapter the colors were quite bad. You could see it most clearly with green Messages and Facetime dock icons which became overly neon green and lost detail. With a 30€ USB-C to DP cable I got color’s that were indistinguishable from RGB mode I got with direct USB-C to USB-C cable.
 
Thanks @theSeb and @aednichols for these inputs

I am in Asia, and you cannot do a no-fault return with online / offline retailers in my country for such monitors, to the best of my knowledge.

I suspect I will have to spring for the LG, unless the YPBPR issue auto resolves.

I do have my U2415, so I can also check as soon as the next release is out.
 
I am not Adam and I do not have the Dell P2721Q, but I do have an older version of this monitor (P2715Q). I also have an old Apple Cinema Display 24" that runs at 1920 x 1200. I can confirm that the difference in text clarity between the two monitors is night and day. I would expect the newer version of the Dell monitor to work the same.

This has nothing to do with colour modes, or M1 Macs, but everything to do with MacOs itself and has been the case for many years.

I cannot comment on colours, since it's not something that is important to me.
No surprise here, going from pre-retina to retina is going to blow away any other aspects of a display.
 
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Thanks @theSeb and @aednichols for these inputs

I am in Asia, and you cannot do a no-fault return with online / offline retailers in my country, to the best of my knowledge.

I suspect I will have to spring for the LG, unless the YPBPR issue auto resolves.

I do have my U2415, so I can also check as soon as the next release is out.
Hey, why don’t we just wait til 11.2 comes out. It should only be a few days. I’ll test and post my results.
 
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Thanks @theSeb and @aednichols for these inputs

I am in Asia, and you cannot do a no-fault return with online / offline retailers in my country, to the best of my knowledge.

I suspect I will have to spring for the LG, unless the YPBPR issue auto resolves.

I do have my U2415, so I can also check as soon as the next release is out.
I mean, displaying obviously wrong colors counts as a defect in my book, but it might be too subtle to convince a business that’s not customer service-oriented.
 
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