Well its more a choice dictacted by budget. You wont get a X800 for $130 so dont try looking.
They make up shapes
When GPUs can crunch out tens of trillions of zillions of polygons per second we need to find a new limitng factor and make that the measuring factor. (also the emergence of dedicated pipes made purely for dealing with polygons and such indicate that polygons arent a limiting factor .... think of rifles: we used to compare them based on rate of fire (think them manual loading old ones) now they they all fire fast we need to find new ways of comparing them (i.e., if you cant dodge 500 rounds/min, yer not dodging 450 either) so we use other things like: silenced, calibre, bullet speed, maintainability etc
Absolute best single card is the 6800U. The X850 is a 12 pipe card while the 6800Gt and 6800U are 16 pipe
