You on,y really need SLI when you have multi monitor setup because you need more VRAM to get the high resolutions without sacrificing texture quality.
ok ,, whats about OC the CPU ? do i need big motherboards like asus maximus v extreme to OC CPU to 4.5GHz ? or any new motherboards will be fine with this OC ? will for me i like asus maxiums v gene so can OC CPU like 4.5GHz on it ?