just use rivatuner to oc,use atitool to scan artifact,use furmark to stress for stability.

after oc,use ati tool for 1-3 hours..no artifacts.if you still want to oc.just oc higher and scan for artifact..if ok d,use furmark for 3-6 hours..bear in mind.cooling is very important..happy ocing and dont oc one time 100 mhz.move little by little..