Steady laminar forced-convection cooling of discrete heated blocks in open and porous matrix channels has been analyzed for different types of coolants, porous material porosities, and mass flow rates. As expected, the low-porosity porous material-filled channel configuration with large Prandtl number fluids flowing at high Reynolds numbers yields the best results in terms of net heat removal. However, the pressure drop for porous material-filled channel flow is measurably higher than that for open-channel flow. As a compromise, using a high porous matrix (say, n = 0.3), the efficiency of the new configuration is 46% higher using water and 58% higher for air when compared with the traditional open-channel cooling system.