The energy consumed in switching the voltage on the power rail (VDD switching energy) is a significant overhead in systems using Dynamic Voltage Scaling (DVS) and/or power gating. In this work we propose and demonstrate the use of Stepped Supply Voltage Switching (SVS) for reducing VDD switching energy. We show the analysis, benefits, and overheads of using SVS for DSP algorithms implemented with voltage scalable adders and multipliers in simulation and silicon. SVS helps achieve 45% and 60% net savings in VDD switching energy while switching from 0.3V to 1.2V using one and two intermediate steps respectively. Power supply noise, another concern in systems using power gating or DVS, is also analyzed. SVS helps reduce noise by over 40%.