I have a 4k monitor and its great, but it won't go to 60hz. I am using a display port cable and my system is fully capable of running 4k 60. I tried changing it using the display adapter properties but when change it 60hz and hit apply, my screen goes black, I lose signal for a second, and then it comes back on, but at 30hz. I don't know what to do and also my cable is in perfect condition so don't suggest that it broke. Another thing to note is that i was running two monitors before and the other one wasn't 4k. The strange thing is that when i had both on the 4k one was able to run at 60hz, but for some reason it can't do that on its own.
my graphics card is a AMD Radeon R9 200 series (not great, but IT CAN RUN 4k 60hz)
