If you are using a Physical Media converter, either an adapter or cable to connect from the RX300/RX-RDP/RX-HDX HDMI port to a Display Port monitor, Please ensure you are using the correct cable.  

Converting from HDMI to Display Port is not the same as converting Display Port to HDMI. The cables and protocol conversion is Uni-Directional, Not Multi-Directional.

Please ensure you are using the correct cable.

HDMI to Display Port would be the correct adapter.