Put on all T5x24 , run the 4-12 version  , overclock them to 1250mhz core and 3100mhz ram and you will have about 300 for all. And run x86 version the most important.
I have 6x750ti overclocked and set to T5x24 and that is the optium , If you try all different cards with different setting you will end up crazy.