A novel framework is developed to determine the optimal operating conditions of water cooled microprocessor chips through a tradeoff between heat recovery from the coolant and the chip thermal reliability. For illustration, a manifold microchannel heat sink is evaluated experimentally and computationally. First, a single objective optimization is demonstrated by combining the heat recovery and chip reliability into a single parameter. Then, multi-objective optimizations are performed by using Pareto optimality and Multi-Criteria Design Analysis. Using conservative guidelines, these approaches suggest that for an optimal coolant flow rate of 1 l/m, optimal coolant inlet temperature lies between 40 and 50 degrees C. (C) 2011 Elsevier Ltd. All rights reserved.