Yes the only way is to software overclock it like with ClockGen, if you see my Dell is overclocked to 2.28GHz that is with software
Be careful and watch temps. Dell's have poor cooling sometimes, and aren't meant for overclocking.
ha nice dude I couldnt use clock gen though, either for 2 reasons (can't remember) there was something wrong with the drivers or it wasnt compatible with my nforce6 chipset...
so i downloaded the nvidia oc tool and autoclocked it from 2.2 to like 2.5 or 2.6ghz
still though hard overclocking is always the best i got my phenom II 940 X4 from 3.0 to 3.5 and im not done - all on stock cooling