well first make sure you can power it, when overclocked that card could draw as much as 350W. Then get MSI afterburner and slowly raise the core clock by 10 MHz increments until it no longer passes 1000 frames of furmark which you run after each increase. then find where it is stable, write it down, and set it back to stock, then do the same for memory. once you have both max values start raising both by 20Mhz or so until you find combined max. BE WARY OF TEMPS THE WHOLE TIME! that card will get toasty, of it is a reference card you might not even want to OC much. if temps are reasonable, then perhaps try raising the core voltage by the smallest amount possible and repeating the previous max clock finding process.