get a pack of .75 ohm resistors look it up super cheap super easy. for some reason on my windows rig all i have to do is attach 1 resistor and extend the desktop to 1 amd card since i do all my other bullshit on my 750ti (which isnt shit for mining but sips on power and does what i need it to).
http://blog.zorinaq.com/the-5-second-vga-dummy-plug/ from the same gangsta who brought you silentarmy mining and trompsolver to make claymore a million fafillion..... ahem, with a great writeup on this exact.... same..... thing..... hit me up on poloniex peace