Yeah, that's usually the percentage gains you get with overclocking the memory. It's not such a linear bottleneck in that you get the same percentage gain with the MHz gains, but sometimes when a bottleneck threshold level is overcome in a certain scenario that is so bandwidth-hungry, there will be a huge boost in performance after overclocking it past a certain level. It only happens in critical scenarios, however. The bottom line is that increasing the bandwidth still does give performance gains. If increasing the clock by 18% gives a 3% boost, then increasing it by 100% could as well give an 18% boost, but that figure is rather low according to the difference between a 5770 and a 4890 despite slight architecture optimizations. A 4890 has 62% greater bandwidth, but performs "only" 20% better.