Originally Posted by Cygnus X

ebay
http://www.alliedelec.com/search/pro...x?SKU=70226232
http://www.alliedelec.com/search/pro...x?SKU=70225934
http://www.alliedelec.com/search/pro...x?SKU=70225889

as with all fans the thinner they are, the more likely they are to break if your just sticking to the chassis with shoegoo or servo tape......thats why i like to go with the 15mm thickness when doing that, if your putting it on a heat sink with 2-4 screws then the thin ones are great, one of them even has higher airflow

next to consider is airflow, when fans are listed at say 5 cfm, that is when its spinning freely, no vibrations, no air resistance....thin fans suffer the most if theres air resistance, thicker fans do much better, what your looking for is static pressure, this is the true power of the fan...this gives you an idea on how the fan will do in a headwind (imagine mounted on a touring car, behind the motor, now it will have to blow towards the front of the car, straight into the airflow under the body.

also thicker fans have thicker bearing surface and in general handle vibration/shocks better than thin ones

HTH