ATI's high-end Radeon X800 cards have been reasonably successful by most measures. The technology is solid and, although a little older, more or less on par with NVIDIA's GeForce 6 series GPUs. They seem to be selling well, with big PC makers like Dell sucking up nearly all the cards ATI can supply. The cards' performance is decent, and ATI's market share numbers are up.
However, not all has been roses. NVIDIA's GeForce 6800 cards have been fierce competition, with the 16-pipe GeForce 6800 GT arguably offering a better value at $399 than the Radeon X800 Pro. Also, ATI's top-end product, the Radeon X800 XT Platinum Edition, has been exceptionally rare. Oh, sure, the streets aren't exactly awash in GeForce 6800 Ultras, but the Platinum Edition has been brutally scarce.
ATI is aiming to correct these availability problems and bring a little more performance to the X800 series with a pair of new graphics chips, code-named R430 and R480. The first products based on these chips will be the Radeon X850 XT and X850 XT Platinum Edition
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As a side note, current reviews cover two of the five new Radeon models expected in the new line-up, currently missing are the Radeon X800, X800 XL and X850 Pro.