Thermal and fluid flow characteristics of a micro-channeled water-block with pass variations in 8 samples were studied. The results of a numerical analysis using ANSYS CFX-11 were compared with the results of experiments. The numerical analysis and experiments were conducted under an input power of 150 W, inlet temperature of $35^{circ}C$ and mass flow rates of 0.7 ~ 2.0 kg/min. The numerical results showed reasonably good agreement, within 3-5%, with the experimental results. Also, the numerical results showed that 2-pass samples give better performance than 1-pass samples in terms of heat transfer. However, the pressure drop for 2-pass samples was relatively higher.