Like the desktop Radeon X1800 XT, the Mobility Radeon X1800 XT has 16 pixel shaders, 16 texture units, 16 render back ends, and eight vertex shaders. The Mobility XT's 550MHz core and 650MHz memory clocks don't quite match the desktop part, though. For the Mobility Radeon X1800, ATI cuts the pixel shaders, texture units, and render back ends to 12. The X1800 still has eight vertex shaders, but core and memory clock speeds are only 450MHz and 500MHz, respectively. Those lower clock speeds should at least allow the Mobility X1800 to work with a wider range of form factors. According to ATI, both Mobility X1800s fit within a 25-35W TDP.
The Mobility Radeon X1800 series will be available in notebooks from Alienware, Boxx, Eurocom, Fujitsu, Voodoo, and others soon, with systems from "tier 1" OEMs following in the April/May timeframe. ATI's CATALYST Mobility drivers will also support the new chips, although it will be up to OEMs to allow the drivers to work with their notebooks.