I have a problem with your DP to HDMI active adapter.
In short: it only work at resolutions of 1080p or less.
I have already tried using a custom resolution with CVT RD timing thru Radeon Settings program. Everthing higher than 1080p I get a few seconds of blank screen and a brief no signal message. Ten system reverts resolution back to 1920x1080 and it works again.
Windows 10 with Creators Update