SemiAccurate claims NVIDIA's upcoming GK104 chip will be smaller than AMD's Tahiti (Radeon HD 7900 series). According to previous rumors, the GK104 will compete against the Radeon HD 7970, while the GK110 will be in a different ball park.
Short story, our favourite ruffled valley mole (Indianfoodus betterthaninminneapolus) didn’t have any callipers handy, so we had to eyeball it with a ruler. The chip we saw is roughly 18-19mm * 18-19mm, putting the range from 324-361mm^2. If you assume it is both square and in the middle, 342mm^2 wouldn’t be a bad number to plug in to the spreadsheets.
While this is a lot bigger than we were expecting, it is still smaller than Tahiti by an appreciable margin. If performance ends up about where we have been told, it will be about as efficient as AMD’s current chips at a lot lower power draw.