1, "220V Cooling Fan" system impedance: range between a cabinet of the air inlet and outlet of the total system impedance of 60-80%, while the greater airflow, noise is relatively higher. System impedance is higher, the greater airflow needed for cooling, so in order to minimize the noise, the system impedance must be minimized.
2, disrupt airflow: spoiler along the path encounter airflow obstruction caused generate noise. Therefore any obstacles, particularly in the critical range of the air inlet and outlet must be avoided in order to reduce noise.
3, "220V Cooling Fan" Speed and size: Because of the high speed fan noise greater than the low speed fan, so you should try and use low-speed fan as possible. And a large size, low speed fan, generally, quieter than small size, high speed fan when transporting the same air volume.
4, temperature: a system that is inversely proportional to temperature required for cooling air flow and allowed. "220V Cooling Fan" allows the slightly higher temperature, can significantly reduce the required amount of wind. Therefore, if you impose the allowable limit temperature rise slightly relax, the required air flow will be reduced, the noise can be reduced.