I have a problem with R7 450 - there are two 4k TV sets connected to it to visualize some SCADA draw (through DP/HDMI adapter, and aproppiate 4k HDMI cable) - there's no probem using AMD's Eyefinity technology to achieve 7680x2160 screen resolution. The problem appears when TV's are switched off - sometimes (not always) after turning on the resolution drops to 3840x1080 (Full HD with Eyefinity), one can see at the moment, that available video modes on graphic card are maximum 3840x1080 (no 7680x2160) what is more interesting is sometimes changes back to 4k automatically (an the list of video modes again show 7680x2160).
Is this a problem with driver (I tried 4 different versions, now it is on 18.3), the card itself, or TV sets?
Thanks in advance.
I have faced this problem too. Change in resolution actually sucks. This problem was caused by the installation of Kodi media player in my tv.
as soon as i removed it. The problem was gone after the restart.