This study investigates the thermal and fluid-flow performance of three microchannel heat-sink configurations: simple rectangular (plain), triangular edge-plate, and zigzag edge-plate. This study aims to cool high-power-density processors, specifically the Intel Core i5-7600K. The processor has a thermal design power of 91 W and a compact die size of about 100 mm². These conditions create significant thermal challenges, requiring efficient and compact cooling strategies. The study uses numerical simulations across a range of Reynolds numbers. It evaluates key performance parameters such as the Nusselt number and the convective heat transfer coefficient. Pressure drop and the thermal performance factor are also analyzed. The results indicate that the plain microchannel has the lowest pressure drop but the poorest thermal performance due to limited boundary-layer disturbance. The triangular edge-plate configuration enhances heat transfer through secondary flow generation, achieving a moderate thermal performance factor of 1.15. In contrast, the zigzag edge-plate design delivers the highest thermal performance factor of 1.20, with heat transfer coefficients increasing by 32.01%–38.21% relative to the plain configuration. Although this improvement incurs a pressure-drop penalty, the zigzag channel still consistently outperforms the other designs, achieving up to 11.77% better performance than that of the triangular geometry at low Reynolds numbers. This study presents a novel geometric approach to MCHS optimization through internal plate integration, offering valuable insights into developing compact, high-efficiency thermal management solutions for next-generation electronic systems.