One of the most important and simple ways to improve the performance of heatsinks is to make small changes in their designs. In this work, considering a reference structure for a pin-fin heatsink, different modes are examined through simulation by shifting the location of input/output currents. The operating fluid is water, and by raising its Reynolds number (Re) number in the laminar flow range (500–2000), functional parameters such as convective heat transfer coefficient (h), distribution of temperature in fluid/heatsink, thermal resistance, performance evaluation criterion value as well as the thermal and frictional entropy generation rates are evaluated. The significant point of the results was that, the geometry in which the inlet and outlet streams were perpendicular to the top plate and on either side of the diameter, and the geometry in which the input and output were placed on two opposite sides (rectangular widths) showed the highest efficiencies. In contrast, the placement of the input/output currents in one direction of the side plate had the lowest performance. Although boosting the inlet flow velocity increased heat transfer, it augmented the production of thermal and frictional entropy (especially frictional) as well as raised the pumping power. The highest PEC value obtained was equal to 1.131, which belongs to the geometry in which the input and output were placed on two opposite sides (rectangular widths) and occurred at Re = 1000.
