I tried 4xAA/16xAF at 1920x1200 with both GTX 280 and HD4870X2... not at all as playable as hoped; while some scenes give nice FPS, when the going gets though the FPS dip well below playable. However I did not include my numbers as I hadn't finished testing all the AA in detail and had some strange numbers, either buggy drivers or buggy bencher;) rather than include unsure numbers I'm going to provide a followup with Crysis AA performance later on:)
it really depends what scene you benchmark what the outcome will be, Techpowerup's did AA tests and included them:
http://img383.imageshack.us/img383/4...6fcfe0cjt9.jpg
they only stated average FPS though but don't provide details on how they tested the game :/
http://www.techpowerup.com/reviews/S...4870_X2/9.html

