lower the timings (lowering generally denotes better performance) and if you get artifacts, immediately set it back to default. this way you know what timings you can tweak and others you cannot. this is a primitive way of testing but its what i did on my 9600pro 🙂 as to what exactly the timings do/mean i would have no idea, maybe ask over at techpowerup.com in the forums where ati tool originates