I'm having similar problems. I am able to play games at 144hz1440p, but I seem to get displaylink failures when the monitor switches between 1440p and 1080p, or fullscreen and window mode or alt+tabing out of fullscreen.
I have an MSI RX 480 8GB Frozr version, and have RMA'd one card already. I have the same Asus MG279Q monitor, and like you I have tried many driver versions and configurations on install, along with different DP and miniDP cables (currently using full DP Startech cable), and clean installs of Win 7 and Win 10. I fared better when I just installed the driver and none of the additional software, but with my newer card it seems to be less sensitive to this so I believe the first card was in fact faulty.
Since changing the card I have yet to experience any crashing, but whenever I have a resolution or window mode swap, it's 80/20 as to whether I will get this Displaylink failure. Once I have this displaylink failure, I cannot go above 60hz until I reboot and is a major PITA.
I'm very keen to see if there is any response from AMD on this one as there seems to be a problem with this graphics card and monitor combination when trying to use 144hz.
Intel i5-3570k (no overclock)
MSI RX 480 8GB
To reset your display adapter after a crash so you can select the right refresh rate, download cru 1.3 and there is a reset batch file that you can use.
That's great, thanks. Will give it a go, would be nice to get back to
keeping a stable up-time.
I am having the same issues as you guys. My gtx 980 died 2 weeks ago so I grabbed an rx480 8gb from Best buy for the time being. I only have had this issue in h1z1 and PU Battlegrounds. I don't have this issue when I play CSGO. When I turn on freesync, my monitor locks to 89.9hz, and I am able to play games, but the moment i turn off Freesync and play at 144hz, my monitor flickers and resets itself to 60hz. I don't even have an option to change it from 60hz back to 144hz until I shut down the game and turn off and on my monitor.