One new feature on the X800 Pro and XT is a new compression technology called 3Dc. 3Dc is optimized to work with normal maps which allows fine per-pixel control over how light reflects from a textured surface. With up to 4:1 compression possible, this means game designers can include up to 4x the detail without changing the amount of graphics memory required and without impacting performance. In a nutshell, it's suppose to provide better looking graphics and faster performance without taking up any extra memory. Of course developers will have to include the new compression technology in their games for you to take advantage of the new feature on the X800 cards.



Link: OCC