It’s good practice in the early stages of designing to take into account airflow requirements for your heat-generating components as well as how much space and power will be needed for your cooling fan or blower.
Axial fans or “box fans” have high performance air flows, relatively good efficiency, and have an axial airflow pattern. Blowers are more effective than box fans for high system impedance that requires a back pressure e.g. network servers and telecommunication systems. Box fans are usually used for low-pressure or low system impedance conditions. This is because they can have a high output of CFM (Cubic Feet per Minute), but at a lower level of air pressure while blowers move smaller amounts of air at a greater level of pressure.
One advantage of box fans is that the noise level can be reduced or increased easily by changing the speed of the fan. These characteristics make them better suited for application in computers. While blowers are known for being noisy compared to fans, what they have over axial fans is a more concentrated airflow. This is a result of the blower’s ability to take air from one side and release it directly onto the unit that requires cooling on the other side.
Blowers are also heavier and more expensive than axial fans.