Tiny Cooling Fan fan quality measure

"Tiny Cooling Fan" fin structure even more complex, it is only a passive heat exchanger; therefore, an air-cooled radiator whether normal "work" depends almost entirely on the fan working condition. Without changing the structure of the other components of the radiator, the only replace more appropriate, powerful fans, so that the cooling effect can also be obtained greatly improved; the other hand, if "Tiny Cooling Fan" with inappropriate or not strong enough, it would be greatly reduced the effectiveness of air-cooled heat sink, so that the heat sink and the overall design of the advantages of being buried in the invisible; even worse, because of "Tiny Cooling Fan" is the only air-cooled radiator indeed part of the "work", Zhu also its own failures will lead to overall failure radiator, so that it lost most of the thermal performance, thereby causing system instability or crashes, or even due to high temperature burning device parameters: For air-cooled heat sinks, fans are so the "critical." So, we should measure the quality of a fan of what information passed?