Apparently this goes back at least 5 years from the posts i've found, although it's new for me:
Fury X using a DP to mini DP (came with the monitor) cable, connecting to my dell ultrasharp u2414h monitor. I was away from the computer and the monitor had gone
into a sleep mode, when i came back and woke it up i found my monitor no longer capable of 1080p60. Anything above 720hd is interlaced only, and if i try and force it i get the above error message. Apparently both the video card and monitor ID each other correctly, but the display modes listed are incorrect, as mentioned in the other posts. Reinstalled all the latest drivers/updates and dis/reenabled all the hardware but no luck. Since i'm not well versed enough to read xrandr code, anyone have a slightly less technical fix that i can understand and implement?