i used to enable it with osx86tools, i stopped doing it because i didn't notice a difference. I've always used nvidia 8600gt or higher video card, i remember back in the day when the 8600gt was like 100 bucks, microcenter had some oem refurbished palit 8600 gt's in @49 bucks and i was buying them left and right, they worked very well! i used NVEnabler and NVKush at the time