This study presents experimental investigation and optimization of heat input and coolant velocity based on the effective thermal conductivity of vertically oriented U-shaped twin heat pipe equipped with cooling fins, employed for PC-CPU cooling. The experimental design and optimization is accomplished by the design of experiment tool, response surface methodology. The results show that the heat input and the cooling air velocity have significant effect on the effective thermal conductivity. When the heat input was increased up to 50 W, the thermal conductivity increased and began to get off with further increase of heat input. For a given heat input, the thermal conductivity was found to increase with the increase of the air velocity up to 3 m/s and thereafter decreased. The results were optimized with the objective of maximizing the effective thermal conductivity, using Design-Expert software, and the optimized heat input and air velocity are 49.03 W and 2.90 m/s, respectively, the maximum thermal conductivity being 23839 W/m K.