What are the factors for Cooling Fan Manufacturer speed play a decisive role

Many customers in the purchase of "Cooling Fan Manufacturer" when are the first thing to consider is cooling fan manufacturer qualification, quality of products, product size, and finally whether the product have had heat performance, but on the "Cooling Fan Manufacturer"the decisive factor in the speed and what it? Axial fan speed and cooling capacity and not necessarily related to higher fan speed but will result in higher noise, if the amount of wind almost, you can choose when you buy low speed cooling fan products "Cooling Fan Manufacturer", in use when will quiet some