Hi, at first of all i want to say sry for my bad english 🙂
I have my ROG SWIFT PG279Q since 4 years or so, since last week i got an issue... when the monitor is connected via displayport 2560x1440 144hz there are stripes on the screen. i will show you with some pictures down below. i tried a new dp-cable, same issue. my 2. monitor is working fine, so i don´t think its my 1080ti. it gets less when i lower the refresh rate to 100hz as you see in the pictures below.
now it even got worse, i see the problem now whatever hz i set, displayport and hdmi same issue. 2. monitor still works perfectly fine... and so you know, the pictures where made with my smartphone, you don´t see the issue on screenshots.