In this paper, the thermal performance of an AntMiner mining machine containing 189 chips on three printed circuit board (PCBs) is experimentally studied. The numerical method is applied to analyze the local airflow and thermal distribution alongside the flow direction and shows a good agreement with the experimental results. Some hot-spot regions are identified where chips might suffer under high-temperature operating condition. Meanwhile, the highly compact arrangement may result in pronounced bypass and jeopardize the thermal performance of the mining machine rapidly; thereby, the airflow management strategy for such confined compartment is implemented. The result shows that the flowrate distribution can be notably improved. Although the total flowrate is slightly reduced by 4.4%, the maximum chip temperature on three PCBs can be reduced by 3.2 °C, 3.5 °C, and 3.0 °C, and the corresponding improvement on thermal performance reaches 13.3%, 15.6%, and 13.0%, respectively. Furthermore, the maximum temperature of the downstream chips will be reduced by 2.5 °C when incorporating the “partial bypass” design by the removal of 12 backside heat sinks. The corresponding heat transfer performance is improved by 8.9–13.9%.