If you download "msi afterburner" and "Furmark" you should be set to clock and test.
One way to do it is raise the clocks in 10mhz jumps and give furmark a blast for 5-10 mins on extreme burn in mode - once your up a around 50-60mhz on the clock speeds it may be better to run furmark for longer than 10 mins at a time to make sure its 100% happy, keep going untill you see any artifacting on the furmark video (for me its usualy yellow pixelations dotted around, drop back 15-20 mhz and run it for an hour or so, if you dont spot any in that hour you should be good to go, jump into your fav game for while and make sure its all stable, if its not drop it back a little more and try again.