You should include information like what operating system you are using, if you are using windows, you need dummy plugs. http://www.overclock.net/folding-home-guides-tutorials/384733-30-second-dummy-plug.html This is how to make them.  If you are using linux and you typed something like aticonfig -i in a root terminal and got only one active, than it could be a hardware related issue (maybe the cards aren't in their ports correctly).