IMAC external display issue

So i have the mid 2015 Retina display i have three of the display port to HDMI adapters and have tried four different HDMI cords along with adjusting settings on both IMac and TV the models are the Samsung MU8500 and they won’t connect at the same time to IMac without both losing signal and singularly the screen will go solid black for a second over and over randomly. Can this IMac not handle these TV’s or is it due to the “connect all” box associated with the TVs? I have also tried to reset the SMC. Please advise...