Poor power quality, slow dynamic response, high device stress, harmonic rich, periodically dense, peaky, distorted input current are the major problems that are frequently encountered in conventional switched mode power supplies (SMPSs) used in computers. To mitigate these problems, it is proposed here to use a nonisolated bridgeless buck-boost single-ended primary inductance converter (SEPIC) in discontinuous conduction mode at the front end of an SMPS. The bridgeless SEPIC at the front end provides stiffly regulated output dc voltage even under frequent input voltage and load variations. The output of the front end converter is connected to a half-bridge dc–dc converter for isolation and also for obtaining different dc voltage levels at the load end that are needed in a personal computer. Controlling a single output voltage is able to regulate all the other dc output voltages as well. The design and simulation of the proposed power supply are carried out for obtaining an improved power quality that is verified through the experimental results.