In this study, the thermal performance of the cooling system of an industrial inverter has been studied using 3D computational fluid dynamics (CFD) simulation in ANSYS Fluent software. An alternative rectangular 17-fin geometry is proposed to overcome the severe thermal stratification and performance limitations identified in a baseline triangular 7-fin commercial design. The simulations are performed across a parametric matrix of inlet air velocities (2 m/s to 8 m/s) and ambient temperatures (25°C to 45°C). The results indicate that the modified rectangular design successfully suppresses localized hot spots by disrupting the continuous growth of thermal boundary layers and eliminating stagnant fluid wakes. At the nominal operating condition (Vin = 6 m/s, Tin=25°C), the proposed configuration reduces the average temperature of the critical component (Chip-5) from 152.2 °C to 110.9 °C, and the fluid wake temperature downstream is lowered within a uniform band of 86.4°C to 106.8 °C. Although the narrow rectangular passages introduce a twofold increase in total pressure drop (54.56 to 56.51 Pa), the aerodynamic penalty remains comfortably within the operational head of standard cooling fans. The proposed design demonstrates an outstanding thermal-hydraulic efficiency, validating its feasibility for high-heat-flux electronic applications.