It looks like there are some efficiency improvements in blackwell. If you power limit a 5090 to use about the same power as a 4090 it’s still much faster. Although I think you can tweak the 4090 in much the same way and lose a few % of performance with a lower power limit. Seems like these things ship well beyond their best point in the efficiency curve, like they’re heavily overclocked out of …

https://forum.beyond3d.com/threads/nvidia-blackwell-architecture-speculation.63097/page-75