I am running Radeon Sapphire HD 7950 which should support four monitors. I have three hooked up right now, one with Dual Dvi, one with hdmi, and one with mini display port converted to dvi. I am running windows 7 64 bit, which detects all three monitors but will only activate two at a time. When I try to activate the third, it merely says, "Unable to save display settings" with no further explanation. I cannot figure out what is wrong.