The present invention discloses a cooling system for temperature control, e.g., removing heat from electronic circuits. The cooling system includes a fan and an airflow guiding system where the guiding system includes an inlet air duct for guiding the airflow to the fan. The inlet air duct includes turbulence reduction grid for separating the air duct into a plurality of isolated flow path whereby the air turbulence is reduced. In a preferred embodiment, the airflow guiding system further includes an outlet duct for incorporating the fan therein wherein the outlet portion and the fan are directed to a direction different from the inlet air duct for guiding the airflow to the fan. In another preferred embodiment, the outlet duct and the fan are directed to a direction perpendicular to the inlet air duct for guiding the airflow to the fan. And, the inlet air duct and the outlet duct are connected via a corner duct-connector having a blunted corner angle for smoothing and reducing airflow turbulence flowing there through. In another preferred embodiment, the fan having a rotational shaft hung to the corner duct-connector whereby the fan is structurally supported only on the rotational shaft for reducing air turbulence. In another preferred embodiment, the fan includes a plurality of blades wherein the blades are configured to have a bending blade surface constituting same direction screw shape for reducing airflow turbulence. In another preferred embodiment, the blades are formed with a notch at a front end of the blades to reduce a reverse flow due to air resistance for further reducing airflow turbulence. In another preferred embodiment, the inlet air duct further includes other openings for increasing a flow rate of the airflow to improve the cooling efficiency.