Nvidia's plan to shift from 65nm to 55nm to lower costs is bearing fruit and we have the first 9800 GT 55nm in our hands. The biggest difference compared to the 65nm verison is its support for HybridPower technology that is not included on 65nm-based 9800 GT cards.
The new core is revision B and it has a smaller die size (55nm - ca. 270mm2 ) compared to revision A (65nm - ca. 330mm2).
During the die shrink on the G92 from 65nm to 55nm nothing in terms of architecture was changed. We still have 112 stream procesors with 16 ROPs. Actually the Geforce 9800 GT is identical to the Geforce 8800 GT, it has the same specifications except HybridPower support on 9800 GT 55nm cards.
We showed you Sparkle's passively cooled 9800 GT card here, but what we did not know at that time is that it was based on 55nm GPU.
We ran GPU-Z and it displayed the specs showing us that Sparkle's card is based on the old 65nm GPU. Later on, we found more time to play with the Sparkle's 9800 GT card, and after we took the cooler off, we saw the 55nm GPU behind.
We have a nice picture where you can see it is physically smaller than previous revision A chip. The one with the blue PCB is Sparkle's 9800 GT, and below you can see an 8800 GT.