Thermal analysis of electric devices is an indispensable operation for determining operational stability. It is especially important for high-speed and miniaturized electronic devices. The analysis should consider the diverse range of operating conditions. It should also include heat conduction within the parts, the air flow inside the case and the exhaust path to prevent hot air from being trapped inside the cabinet. Using a combination of HeatDesigner and scSTREAM, various combinations of fans and opening positions can be compared.