Heat transfer in electronic systems is studied by simulating flow in a two pass channel with the divider representing a circuit board. Bypass holes are introduced on the circuit board to obtain detailed physical insights of the reversed flows in the second pass and thereby improve the cooling effect. The time-dependent governing equations are solved using an in-house code based on Streamline upwind/Petrov-Galerkin finite element method for Reynolds number ranging from 100 to 900. It is observed that stagnant zones are formed in the return path along the upper heated wall due to the formation of primary recirculation region on the divider plate. These stagnant zones are convected downstream by introducing bypass slots thereby enhancing the convective cooling. A parametric study on the location and number of bypass slots reveals that for a particular combination, the flow becomes unsteady thereby the heat transfer is increased. The presence of multiple slot jets also reduces the overall pressure drop required to drive the flow and heat transfer is very high at the point of impingement between the slots.