RX Vega 64 drops frame occasionally on 4K display

[WuTian]

Hello, guys

I'm using a RX Vega 64 Air Cooling black reference card, when I connect my Dell U2718Q 4K display to the DP port of the Vega card, I noticed the UI become laggy compare to the 2K display(U2515H) I used before:

- The UI drop frames every 3 seconds
- I can see a error message from Console.app every 3 seconds
kernel: AMD Error:
kernel: Failed HDCP: status 4

I'm currently running latest macOS 10.13.4 and my EFI folder is almost identical to pastrychef's EFI for AMD RX500-Vega r3.2.zip
https://www.tonymacx86.com/threads/...wi-fi-ac-build-w-i7-8700k-amd-vega-56.239969/
SMBIOS: iMac18,3
CPU: I7-8700K
Mobo: Rog Strix Z370-I

And I tried following things, but issue still persists:
- Use different SMBIOS: iMacPro1,1; iMac14,2; iMac18,3
- Enable or disable IGPU from BIOS
- Different combination of kexts:
- Lilu.kext; WhateverGreen.kext; VegaGraphicsFixup.kext

But the issue do NOT appear when I use one of the following configuration:
- Connect 4K display via HDMI (the HDMI port only supports 30FPS, so I can't use it)
- Only 2K display via HDMI or DP

Since the error message from Console shows it's AMD Graphics Card HDCP issue, I also tried find way to disable HDCP or properly enable it, but with no luck

Do you have any idea how can I solve this?

Thank you!

 

[Quad3000]

I had a similar problem with my Vega 64 after I first installed it. It would "stutter" once in a while. What seamed to have worked was going to System Preferences/Accessibility/Display and then select and de-select Reduce Transparency.

I have no idea why it did what it did, but I'm 95% sure this trick fixed it for me.

PS: I have the same Dell 4K monitor connecting via a dp to mini-dp cable.

 

[pro4jhu]

i have the same problem with intel graphics, did you solve now?

 

[WuTian]

i have the same problem with intel graphics, did you solve now?

I can't find a solution, so I returned the card at the end...

 

[pro4jhu]

is the card problem? what card did you use now , have the same problem?

 

[WuTian]

is the card problem? what card did you use now , have the same problem?

This issue only happens when using Vega card with U2718Q using my specific Clover EFI config, I'm not really sure which one cause the issue.

I'm currently using Pulse RX 570, which don't have this issue, and it's way quieter, stable than the Vega card I've tried.

 

[TomHsiung]

How about to try HDMI port?

 

[WuTian]

How about to try HDMI port?

The HDMI port don't have this issue,
But seems HDMI can't output 4k/60Hz on macOS, and U2718Q is a 4K display, so I need to use the DP port.