Radeon8500 will put up with fastwrites enabled on some systems without error.. 3dmark will note that it's disabled when you have it enabled, sisoft sandra will note you can use it when its disabled then turn around and say your card DOES NOT SUPPORT it when you enable it.. fact is Radeon8500 does not take any advantage of Fastwrites what so ever.. so best bet is to leave it off and save your self some problems.. and this goes for all chips sets not just Via..