Adding GPU or GPU's

Hi i am currently looking to buy graphics cards i play at 1920x1080 i play battlefield 3 and crysis 1 and 2
i had SLI GTX 560 TI setup but never could get it to work right. first bridge that came with mainboard the drivers would reconize both in SLI but screen with flicker. i bought a second sli bridge but it think i tore it and it fulscreen in battlefield 3 it flickers purple on the top of the screen. and in crysis 1 i can hit alt and enter about four times and the purple will go away.

any suugestions on a new set of single card