Sapphire RX480 Nitro - HDMI dual monitor problem

I have a problem when connect dual monitors into HDMI port (Connect 2 monitors into HDMI port using VGA to HDMi converter) It's alaways blinking.

This issue doesn't occurs, when only using 1 monitor.

 

Hardware & Software :

  • Graphic Card : Sapphire RX480 Nitro 4GB
  • VGA Driver : Radeon Software Version 6.12.2
  • Monitor : 2x (Dell E170S) Resolution 1280 x 1024
  • Connector : VGA Cable + HDMI to VGA Converter
  • Operating System : Windows 10 64bit

See attachment "Video Problem.mp4" to see problem details.

 

Please, help me to solve this problem. Thank you very much.