We're talking about AMD 790/890/990 northbridge chip here. The "gen" here didn't change, just the fab process. So it's an optical shrink. The transistor count is the same. If you want an example of optical shrinks, don't look at Intel CPUs, look at NVIDIA GPUs. Clock-for-clock, G92b (55 nm) was cooler and drew less power than G92 (65 nm). There were no transistor count changes between them.