Lower VID has more overclocking headroom as you have more volts to play with, though typically as you increase volts, a lower VID chip heats up more quickly than a higher one, so you need good cooling (often water) to take it to its potential. So, if you're air cooling it's probably swings and roundabouts unless it's a particularly high VID without much voltage headroom for safe 24/7 OC. There is a general correlation with VID and OC ability, but for an average clock you're not going to have much trouble with a G0 chip, though I hear the newer ones aren't as good as the older batches of G0s. If it's a B3, get rid, in general they're not good clockers and use more power.