On Mon, 20 Jun 2016 21:16:48 +0800, Mr. Man-wai Chang wrote:

On 20/06/2016 8:13 PM, Allan Herriman wrote:
Caveat:
Until the fans "fly" they are just like crappier-than-normal sleeve
bearings.
Expect lots of wear below a minimum RPM (that I don't think is
specified in the datasheet, although they may specify a minimum voltage
or PWM duty cycle).
Start and stop cycles will also cause wear.

How do you guarantee it to spin at maximum speed?

Do not reduce the PWM below the recommended minimum. Or do not reduce
the voltage below the recommended minimum.

The fan that the OP linked actually specifies an RPM range (400 - 2400),
so it would be acceptable to reduce the PWM duty cycle as long as the
speed is above 400RPM.

Regards,
Allan