UPDATE: I have jsut directly connected my 3rd screen to the video card using an HDMI cable and I can see it in Display settings but when I try to enable it to expand the screen windows says "These display settings cannot be saved". The Catalyst control center has now labelled my two working displays as "Display 2" and "Display 3" but I can't see anywhere to change it's settings.
I have purchased a DisplayPort to HDMI Adapter to hook up a 3rd display to my Radeon HD7800 graphics card.
Windows/AMD does not seem to be recognizing the 3rd monitor, when I do a detect it does not show. I have the latest graphics driver and am running Windows 8.1 x64
Any idea? No matter which monitor I try with the adapter it does not work, even after rebooting. My PC Power options and the Radeon settings are both set to high performance.