I believe that many "Micro Cooling Fan" of buyers and cooling fan manufacturers are aware of, oil bearings and ball bearing cooling fan, that first of all we start to identify the bearing, oil bearing lower prices turn voice is small, some manufacturers Suppliers within the oil-bearing plus Teflon, making the cooling fan also has a ball bearing reliability, and sell high. Ball bearing fan noise ratio of oil-bearing, the price is relatively expensive, but more reliable, universal service life longer than the oil bearing, but some "Micro Cooling Fan" manufacturers in order to save costs, originally a double ball bearing The privately only one ball at a fan installed inside, because the case without the knowledge of the customer, sell at high prices. Second, look at the ventilation rate, some of the cooling fan buyers always thought better cooling fins, in fact, this is a mistake The concept has the advantage of a large fan blades long, heat dissipation area, so the larger gas flow. But if not properly designed, big fan of cooling capacity may not be as good a small fan. Finally, look at the heat "Micro Cooling Fan" one fan blade if other parts remain unchanged, only the blade consists of five blades instead seven blades, wind changes may not add much.