The X850 generation of cards comes from optimised R423 silicon powered with additional power management features. Don’t forget ATI is using new cooler and thermal throttling marchitecture. See this below.
The fastest of them all, the Radeon X850XT Platinum edition is clocked to not that an impressive 540MHz core and 590/1180MHz GDDR 3 memory. The card has two DVI slots for two TFTs.
More information and a photo of the X850 can be found here. Some information regarding the prices of ATI's upcoming X850 series can be found here.