with my old gpu 8800gt i could overclock it and tweak the fan rpm with riva tuner but i recently installed a new gpu (gtx 460) and non of those options are available in rivatuner anymore..
Rivatuner is outdated and don't support the latest drivers. Download MSI afterburner (here) or EVGA precision here/b]) both works excellent, but I prefer the 1st one.