The Max safety one is easy. The most safiest is where the manufacturer, ATI (ATI RULES!!!), sets it. Underclocking it can freeze it up, overclocking it can damage it. Now this is just an estimate, they say that the safest you can do if you are going to overclock it is between 5% and 25%, but if I were you, i wouldn't do it. Or I would search on the internet, do a google search, and see what you come up with.