A passive heat sink for use in a portable personal computer includes a thermal mass, such as an aluminum plate, that is adapted to make thermal contact with the CPU or IC, whose temperature is to be regulated. The thermal mass is formed to enable excess heat from the CPU or integrated circuit to be channeled away by thermal conduction from the CPU or IC and dissipated or released in the computer housing, such as the keyboard, which can tolerate limited amounts of heat. In order to accommodate CPU's and IC's of different thicknesses, a thermally conductive spacer, for example, formed from copper, may be secured to the CPU or integrated circuit by way of a thermally conductive adhesive, and, in turn, placed in contact with the thermal mass. With such a configuration, the space requirements for the heat sink within the portable personal computer for cooling are minimized, while the expense of more expensive cooling systems such as heat tubes and Oasis-type cooling systems is obviated.