We have a 4K display composed of 4 1080p displays linked together. When a slide fades out and a new slides fades in, there are small lines that pop up for a second as the slide fades in. One the slide is full displayed, the lines stop. The content is being displayed from Four Winds digital signage. I notice these lines will also appear on the desktop but not as prominently or as frequently. I have tried to adjust the core clock and memory clock but this has not alleviated the problem. The card is a Gigabyte R9 390 with 8GB of RAM. Current drivers are installed.
I have tried to shoot video of this but it is a bit tricky. I may be able to post a still image of the lines though.