The switched mode power supply converters were utilized tremendously in recent years especially DC-to-DC converters, due to their high conversion efficiency and lightweight. These converters can have single or multiple outputs according to the application. The present work treats the design implementation and simulation of a resonant DC-to-DC converter for computer power supply. The design and performance of individual components of the converter were discussed. With particular reference to 200 W prototype with +5 V, -5 V, +12 V and -12 V DC voltages that are namely the voltages needed by the motherboard, drivers (floppy drives), hard disk and other computer basic devices that uses one or more of the above mentioned DC voltages. The converter switching elements were two MOSFET transistors connected as a half-bridge operating at a maximum frequency of 100 kHz. The converter is controlled using a switch mode pulse with modulation control integrated circuit. Also in this work, the operation of the designed circuit was tested after (simulation) using the software package Design Center (virtually a modification of the well-known PSPICE package that works under Windows 98). Finally, the performance of the complete prototype converter is assessed where it is determined that the power electronics and control circuit considered have stable efficient and reliable operation over various operation conditions.