hi all! i bought an open box saphire radeon 7870 oc edition card and i was looking to put it through a stress test to make sure the card worked as needed what i was wondering is if there is a good free program for benchmarking and stress testing that i can get, are furmark and 3dmark free? also is it just pointless to do for someone not reviewing? the card works so far and overclocked slightly without hesitation but i just want to be sure before my 30 day window is up. thanks for the help!