The EVGA Voltage Tuner will enable users to adjust the voltage of their cards in a range from 450mV to 1350mV, giving you assistance in overclocking or underclocking of EVGA GeForce graphics cards.
According to Jacob Freeman from EVGA, the tool enabled him to increase the core speed of an air cooled GeForce GTX 295 by another 100MHz. At the standard voltage of 1038mV, Freeman overclocked the core of his card to 684MHz and the shaders to 1476MHz. By boosting the voltage to 1263mV, he got the core clockspeed to 783MHz and the shaders to 1692MHz. More info and screenshots at EVGA.