Wheres the definition for AF too VIII
AF is Anisitropic Filtering, helps for the scene in the background to be clear.
P.P. .........jeez, 1600x1200 resolution and you're wondering why it slows down at 8x AA, yeesh, and I suppose you're trying to do it on Ultra settings too? That's just ridiculous stress on any card.
Get SLI and theres a way to force Doom3 to run at like 2048x1600, I heard THAT looks just freakin amazing to the point even where the developers were amazed, but they ran that using a 6800Ultra so theoretically yours should handle it too