Solved > Colour banding issue on 4K display

[Bustycat]

Original title: 4K display HDMI and DisplayPort issues with RX 580

I just bought a 4K display (Philips 276E8VJSB) and it worked well on Windows 10 (version 1903). The display connected with an HDMI 2.0 cable will not have any signal immediately after booting into macOS 10.14.5, but the signal could be recovered by easily replugging the HDMI cable.

I also have tried a DisplayPort 1.4 cable today, and the problem mentioned earlier is solved. However, many of elements of the macOS user interface like the translucent sidebar would display only 4-bit colours (supposed to be 10-bit), resulting in colour banding, yet other things like images are not affected. Screenshots would not show the problem.

I used only MultiBeast to set my computer. Now I have to stay with HDMI as colours are more important than convenience for me. Although the issues are somehow minor, they are annoying to me. Sleep/Wake, however, always work well.

I would appreciate so much if one of them could be properly resolved.

Update: The DisplayPort colour banding issue is fixed via #19, and it may happen on different scenarios as well. The HDMI issue is on hold as it is currently not possible to determine where the problem is.

 

[Bustycat]

Methods I have tried but failed:

• Rebooting
• Turning off and on the display
• Two different HDMI cables
• All HDMI and DisplayPort ports on both of the display and the graphics card
• https://www.tonymacx86.com/threads/fix-corrupt-color-depth-in-high-sierra-mojave.262495/
• https://discussions.apple.com/thread/8094122?page=3
• macOS Mojave installer (only booting)
• Different model identifiers (now iMacPro1,1)
• ResXtreme
• Orinoco framebuffer
• Windows 8/10 WHQL in UEFI/BIOS

 

[pastrychef]

Methods I have tried but failed:

• Rebooting
• Turning off and on the display
• Two different HDMI cables
• All HDMI and DisplayPort ports on both of the display and the graphics card
• https://www.tonymacx86.com/threads/fix-corrupt-color-depth-in-high-sierra-mojave.262495/
• https://discussions.apple.com/thread/8094122?page=3
• macOS Mojave installer (only booting)
• Different model identifiers (now iMacPro1,1)
• ResXtreme

Please post your EFI folder and a screenshot of what's in your /Library/Extensions/ folder.

HDMI has always proven to be a bit unreliable for me. In my experience, DisplayPort has always worked much better.

Also, have you tried injecting Orinoco framebuffer to see if colours are improved?

 

[Bustycat]

Please post your EFI folder and a screenshot of what's in your /Library/Extensions/ folder.

HDMI has always proven to be a bit unreliable for me. In my experience, DisplayPort has always worked much better.

Also, have you tried injecting Orinoco framebuffer to see if colours are improved?
View attachment 416018

Here is the CLOVER folder and the screenshot. Sorry I have forgot what the tool is.

I do want to use DisplayPort more if there is no colour banding. I spent extra money on the cable.

 

[pastrychef]

Here is the CLOVER folder and the screenshot. Sorry I have forgot what the tool is.

I do want to use DisplayPort more if there is no colour banding. I spent extra money on the cable.

Please make a backup of your existing EFI folder and try this EFI folder to see if it helps and remember to try with/without Orinoco.

 

[Bustycat]

Please make a backup of your existing EFI folder and try this EFI folder to see if it helps and remember to try with/without Orinoco.

Unfortunately this does not solve the problems for HDMI and DisplayPort at all. Should I still try Orinoco and how should I try it?

 

[pastrychef]

Unfortunately this does not solve the problems for HDMI and DisplayPort at all. Should I still try Orinoco and how should I try it?

Just edit your config.plist > Graphics section as shown in post #3.

 

[Bustycat]

Just edit your config.plist > Graphics section as shown in post #3.

Sadly it still does not help. Problems remain.

 

[pastrychef]

Sadly it still does not help. Problems remain.

Bummer... I don't know what else can be done...

 

[Bustycat]

Bummer... I don't know what else can be done...

Is that related to the driver of RX 580? Those don’t happen at all on Windows.