Just got my RX580 8GB and I'm testing some games, Ride 2 in this case, and I noticed that Radeon custom anti aliasing settings are performing very badly. I know gif is not the best format to show imagery but for convenience sake I made a gif cycling thru 3 different modes I tested and cropped from original 1440p screen grabs. The color loss compared to original png's is not that drastic, gradients - but how you see the differences in anti aliasing is how I see them myself, the gif quality loss is insignificant.
So why is this the case, why does Radeon AA perform so obviously worse than in game? Of course the in game AA was off when Radeon AA override was active.