I have an Acer display whose native resolution is 2560x1440 @ 59 Hz, which I have been using with a DisplayPort-certified Accel cable, and I've been using it with my previous card, to rule out problems with the DP cable operating at such a resolution. The problem is, using either of the DP ports on my Sapphire Nitro+, at random points it will begin to flicker constantly on the desktop. If I change the resolution from 2560x1440 to 1920x1080 and then back to 2560x1440, I will also lose a signal to the display until I unplug the cable and plug it back into the card/monitor, and turn the monitor off and on again. This happens in both Windows and Linux (Linux 4.8 + Mesa 12), which leads me to believe that it's a hardware or firmware problem, rather than a driver problem. I've attached a sample video showing the behavior, which is rather annoying.