Method and apparatus for decoupling of unused power supply pins of a printed circuit board capable of operating at a plurality of predetermined voltages

A printed circuit board (PCB) capable of operating at first and second predetermined voltage levels including a plurality of metal layers, one of the metal layers being divided to provide two electrically isolated sections, the two electrically isolated sections being on substantially the same plane; one of the electrically isolated sections being associated with the first predetermined voltage level and the other of the electrically isolated sections being associated with the second predetermined voltage level. The PCB includes a first plurality of signal pins coupled to the one of the electrically isolated sections. The PCB also includes at least one capacitor coupled to a ground plane, the first plurality of signal pins and the one of the electrically isolated metal sections, wherein an alternating current path is provided. The PCB in a preferred embodiment is an expansion board utilized in a personal computer.