Connected dual monitors via DP1.2 using UltraAV mDP to DP cable with screens in extended mode. Result , both monitors flash black screens intermittently and randomly-  either or both then eventually show only a black screen. Any solution available? Both monitors seem to have no problem operating in DP1.1 individually, so issue only arises when DP1.2 enabled and daisy chained. Had initially tried the DP cable which came with the monitors but changed to UltraAV to see if this would cure the problem ( it didn't). Monitors made in August 2014 Rev A00 serial numbers CN-74261-480-3TCL and 48S-130. PC Alien R3 desktop as built but replacement Dell m/b DP/N 046MHW. Graphics card R6870 2x mdp, 2x VGI and 1x HDMI ports.Windows 8.1. Monitors using recommended resolution and self test showed no problem. Monitors purchased via Amazon. Tried factory reset which disables DP1.2 but have to reinstate DP1.2 to daisy chain but same result.