Good day maximwertt,
In general:
A HD7850 card will standard support 2 screens, if you want to connect more screens you will ned to enable the “Eyefinity” feature, you do that by using (one of) the DP ouputs of the card. In this thats an easy one 😉
When using screens with DP input, you can just connect with “normal” or “passive”adapter / cables. When using screens without DP input you will need active adapters/cables with eyefinity support from the 3rd screen onwards.
So for use of screens without DP input it should be like this:
Screen 1: Connect with “normal/passive” adapter / cable
Screen 2: Connect with “normal/passive” adapter / cable
Screen 3: Connect with active adapter with eyefinity support + normal HDMI cable
Screen 4: Connect with active adapter with eyefinity support + normal HDMI cable
Screen 5: Connect with active adapter with eyefinity support + normal HDMI cable
Screen 6: Connect with active adapter with eyefinity support + normal HDMI cable
Active Adapter with eyefinity support:
CAC-1170 = Mini DP to HDMI 2.0 Active Adapter with eyefinity support
http://www.club-3d.com/index.php/products/reader.en/product/mini-displayport-12-to-hdmi-20-uhd-active-adapter.html