The new monster features 312 millions transistors vs. "only" 157 millions for the Radeon X1600 Mobility. The XT model has 16 Pixels Pipelines vs. 12 for the X1800 (also 12 for the X1600). It also get an additional vertex shaders unit compared to the X1600. The XT model is clocked at 550MHz vs. 450MHz in the non-XT model.
The main difference between the X1800 and X1600 is the memory bus that goes from 128 to 256 bits, doubling the theoretical maximum data flow rate between the GPU and its dedicated memory.
This is the perfect notebook-specific graphic card to find its place together with the Merom in the future MacBook Pro revision (potentially at the end of 2006).
