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2019 Macbook Pro Radeon Vega 20 graphics unstable/flicking on Samsung CRG90 49"

Question asked by islack on Jan 14, 2020

I'm facing video instability and inability to use my CRG90 monitor on my Macbook Pro with radeon vega 20 graphics. Leading to video flickering, see this video.

 

This has been troubleshooted in depth including:

- replacing all displayport cables

- replacing all dongles (usb-c to displayport - startech CDP2DP)

- reimaging to vanilla MacOS 

- macbook pro hardware swapped twice... a non radeon macbook pro from 2017 has no issues!

 

2019 Macbook Pro 15 inch

macbookpro15,3 (also tested with macbookpro15,2 and same issue)

32gb memory

2.3ghz core i9

Radeon Pro Vega 20 (device id 0x69af - revision 0x00c0)

VBIOS 113-d20601MA0T-016

EFI driver version 01.01.087

MacOS Mojave 10.14.6 (also tested broken in Catalina 10.15.2)

 

Samsung CRG90 49" QHD monitor LC49RG90SSNXZA

Current version: m-RG949CCAA-1004.0

Configured with default settings (reset), only PBP enabled using DP1 and DP2 inputs.

Macbook Pro USB-c connectors for video, one on left side bus and one in right side bus.

 

This behavior and instability only occurs in MacOSX - Windows is stable with the above setup!

Please help identifying this issue and correcting it in the driver as I cannot use my monitor.

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