ASrock H77 pro4/mvp on-board graphics for third monitor

Hi i recently bought an asrock h77 pro4/mvp which has built in graphics. I have a HD7850 installed which supports 2 monitors through non-display port connections.

When I built another machine recently for a friend I bought him a second (very cheep low end) graphics card so he could do 3-4 monitors without having to worry about display-port adapters etc as a second graphics card can act simply as an output device (all processing is still done on main card, the second card is just pumping this data out to its ports)

I was wondering if anybody knows if/how I can use the built-in graphics in my motherboard in a similar way to this "output card" that I put in my friends machine.

Thanks for any help