ATi Radeon X850 XT Platinum Edition
The Architecture & Features
The R480 chip at the heart of the Radeon X850 XT Platinum Edition is basically a re-spin of the R423 tweaked to take advantage of improvements made to ATi's (TSMC) manufacturing process in an effort to improve yields. Other than the slight alterations made to the core to allow for higher clocks and the addition of some new power-management features, ATi hasn't made any significant changes with the R480...
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The R480's optimized silicon has the same base feature set as the R423 that powered the X800 series of PCI Express cards that came before it. We've outlined the R420's features extensively in our coverage of the X800 launch back in May (R420 is the AGP variant). For a more comprehensive explanation of features like 3Dc, temporal AA, and other ATi technology, we recommend checking out that link. The R480 is still built using a 0.13-micron manufacturing process and it still has 16 parallel pixel pipelines, six hardware vertex shaders, and a 256-bit memory interface. And the 2D engine, video processing engine, and display interfaces are all essentially unchanged.
Like the R423, the R480's pixel pipelines are also arranged in four quadrants of four pixel pipelines, which lets ATi disable individual quadrants if necessary. This ability allows ATi to get more usable dice per wafer because dice with only a single defective quadrant, for example, are still usable if they'll run at acceptable clock speeds. Shutting down quadrants also allows ATi to scale down the GPU and release 12, 8, or 4-pipe variants of the same core. Although releasing an 8- or 4-pipe R480 would be a monumental waste of silicon...
ATi's ability to scale the R480 core has resulted in the three new video cards that currently make up the X850 Series. The flagship card is the X850 XT Platinum Edition with 16 pixel pipelines, a 540MHz core, and 1.18GHz memory. These relatively high clock speeds give the X850 XT PE a higher peak fillrate and more memory bandwidth than any other consumer-class video card released to date. The X850 XT is essentially the same as the Platinum Edition but with a lower clocked core (520MHz) and 50MHz (100MHz DDR) slower memory. Then comes the X850 Pro, which is identical to the X850 XT, minus four pixel pipelines, and with a single-slot cooling solution. Look at little further down the chart and you'll find the new X800 XL and X800, which we suspect many of you will like very much...read on...
