My monitor is 28in Samsung U28E850R, connected to my pc via mini display port came with it. It always black out after I turned it off while downloading things on pc, then it wouldn't turn back on later, the screen stays black out unless I reboot the pc. Happened everytime if I left it off for a while then turn it back on. And the screen also flashes instantly if I connect the it with pc via display port male to male cable, I couldn't do anything with it. The describtion of the cable on MSY site it says it supports up to 3840 x 2160 resolution so this shoudln't be happening, no idea what caused this. This is the one I have:
http://www.msy.com.au/pc-accessories/14288-partlist-pl-dphdmi5m-5-meter-displayport-to-hdmi-cable.html
But if I left the screen on , it would go to screen protecting animation afrer a while and go back to desktop if I move my mouse or press a button on my keyboard, no issues.
Is the issues within the monitor or cable, or is it just I didn't set it up right? I turned on the free sync, GPU scaling, scaling mode full panel, color temperature 6500k, card is Sapphire R9 390 Nitro 8GB.

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