move it up 5-10 mhz on core and then test with 3dmark or something and look for graphical anomalies (aka artifacts). If you see none and it is stable then go higher. Rinse and repeat. Once you reach the max on the core find out what is the max
oc you get while remaining stable and artifact free.
Then put the core back to defualt. then, do the same thing to the memory.
Then find a compromise between highest core and highest mem that is stable and offers best performance.