Gefore 650


6 = the series number ( 600 series)

610,620,630 = Entry level cards (Facebook,flashgames, stream video)

640,650,660 = Mid Level cards( general Gaming)

670,680,690 = High end cards ( High end gaming, Video Processing)

Last generation it was 4 numbers

8= Series number(8000 Series)

8100,8200,8300 = low end

8400,8500,8600 = mid level

8700,8800,8900 = high level

the GTX,gt and all that nonsense is jsut different specs/chip sets and power usuage but thats the general.

Not sure what nvidia will do after 900 series They kinda mess themselves up trying to be fancy and starting in the thousands..