Like the RV670 before it, the RV770 is fabricated at TSMC on a 55nm process, which packs its roughly 956 million transistors into a die that's 16mm per side, for a total area of 260 mm². The chip has grown from the RV670, but not as much as one might expect given its increases in capacity. The RV670 weighed in at an estimated 666 million transistors and was 192 mm².
Of course, AMD's new GPU is positively dwarfed by Nvidia's GT200, a 577 mm² behemoth made up of 1.4 billion transistors. But the more relevant comparisons may be to Nvidia's mid-range GPUs. The first of those GPUs, of course, is the G92, a 65nm chip that's behind everything from the GeForce 8800 GT to the GeForce 9800 GTX. That chip measured out, with our shaky ruler, to more or less 18mm per side, or 324 mm². (Nvidia doesn't give out official die size specs anymore, so we're reduced to this.) The second competing GPU from Nvidia is a brand-new entrant, the 55nm die shrink of the G92 that drives the newly announced GeForce 9800 GTX+. The GTX+ chip has the same basic transistor count of 754 million, but, well, have a look. The pictures below were all taken with the camera in the same position, so they should be pretty much to scale.
Yeah, so apparently I have rotation issues. These things should not be difficult, I know. Hopefully you can still get a sense of comparative size. By my measurements, interestingly enough, the 55nm GTX+ chip looks to be 16 mm per side and thus 260 mm², just like the RV770. That's despite the gap in transistor counts between the RV770 and G92, but then Nvidia and AMD seem to count transistors differently, among a multitude of other variables at work here.
The pictures below will give you a closer look at the chip's die itself. The second one even locates some of the more important logic blocks.
As you can see, the RV770's memory interface and I/O blocks form a ring around the periphery of the chip, while the SIMD cores and texture units take up the bulk of the area in the middle. The SIMDs and the texture units are in line with one another.
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