Did you select DP1.2 via the menu of the monitor?
http://nl.hardware.info/reviews/594...monitor-review-echt-groot-beeld-aansluitingen
cgmaster - Can you link the exact adapter you bought? 4k @ 60Hz: The struggle is real.
Ok I've ordered one if these adapters too so thank you for the recommendation.Sure, I bought this one:
http://www.amazon.com/Cable-Matters®-DisplayPort-Thunderbolt-Compatible/dp/B00C7RJQPY