Hi Ligti, it depends on the application. If you want to connect 4 to 6 4K UHD monitors via DP you can achieve 60Hz refresh rate. Use the CAC-1110
If you want to connect HDMI monitors it’s essential to know if they support HDMI 2.0. If the don’t you can achieve 4K UHD at 30Hz max. Use the CAC-1154
If the screens support HDMI 2.0 you can achieve 4K UHD at 60Hz using the CAC-1170 (available by end of December).
However please note that one HD 7850 may be slightly underpowered for a multi 4K monitor setup!