Anyone who hasn't seen benefits across the board from overclocking a V5 must have a slow processor limiting performance, not the video card. I overclock my V5-5500 to 192MHZ, and I see substantial performance gains in every benchmark and game I have tried. If you are not CPU limited, you'll see great gains. I will say however, that most people will not see 192MHZ with their cards, I got lucky and have a couple of really good cores on mine.
OCnMan