I have 3 Asus VE248 monitors.  I have a HIS 6950 and a Sapphire 6950 Flex (primary card) in Crossfire.  I have one monitor hooked up to my HDMI port, one monitor hooked up to the Mini-Display port with 
this converter cable, and one cable to my DVI port (though I also have 
this cable that I can use).  The problem I am having is that the 3rd monitor is disabled.
What can I do to fix it so I can have 3 monitors to play games on?