In a competition at Carnegie Mellon University, the mechanical engineering students designed and manufactured 27 heat sinks. The heat sinks were then tested for thermal performance in cooling a mock processor. A heat sink with three rows of 9, 8, and 9 dimpled rectangular fins in staggered configuration performed the best, while having the least total volume (about 25% less than the set value). Validation of the observed thermal performance of this heat sink by experimentation and numerical simulations has motivated the present investigation. Thermal performance of the heat sinks with and without dimples have been evaluated and compared. Results of both the measurements and simulations indicate that dimples do in fact improve heat transfer capability of the heat sinks. However, dimples cause more pressure drop in the air flow. Keeping the total volume of the heat sink and the height of the fins constant and changing the number of the fins and their arrangement show that there is an optimum number of fins for the best performance of the heat sink. The optimum fin numbers are different for inline and staggered arrangements.