A three-dimensional heat sink module design problem is examined in this work to estimate the optimum design variables using the Levenberg-Marquardt Method (LMM) and a general purpose commercial code CFD-ACE+. Three different types of heat sinks are designed based on the original fin arrays with a fixed volume. The objective of this study is to minimize the maximum temperature in the fin array and to determine the best shape of heat sink. Results obtained by using the LMM to solve this 3-D heat sink module design problem are firstly justified based on the numerical experiments and it is concluded that for all three cases, the optimum fin height H tends to become higher and optimum fin thickness W tends to become thinner than the original fin array, as a result both the fin pitch D and heat sink base thickness U are increased. The maximum temperature for the designed fin array can be decreased drastically by utilizing the present fin design algorithm. Finally, temperature distributions for the optimal heat sink modules are measured using thermal camera and compared with the numerical solutions to justify the validity of the present design. (C) 2010 Elsevier Ltd. All rights reserved.