Good day avi1587,
Normally setups like yours work best by making a custom resolution in the Crimson fdriver for 3840×2160 at 60Hz and Timing Standard set to CVT-Reduced Blanking.
We have heard of some issue with the latest AMD Driver Updates, so if the above does not fix it, please do this:
Especially by using update-feature for drivers, old files remain in the register that could be “in the way”. Please uninstall the Graphics driver and all related Graphics software like Afterburner/GPU-Z or whatever graphics related software you might have installed.
Best way to remove Driver Software is to boot Windows in Safe mode, so the registry can also be cleaned.
When you system does not allow you to do that, you can also use a program like DDU to remove such software: http://www.wagnardmobile.com/DDU/
When done please download and install driver 16.8.3 yourself (don’t let Windows or any other auto-installer do that):
Here is our latest checklist for your reference: