Originally Posted by psyclum
i dont know about the AP121's. but the AP181's are actually quite loud. on low setting, you can definitely hear the motor of the fan. to bring it to quiet levels, you'll need a fan controller to bring it down to 500 rpm on the AP181's
as for whether it'd make a good rad fan, I'd have to say no. better designed fan like GT's would be much better for rad fan. the channeled air flow seem like a good idea for rad fan, but the fact is the channeling of the air increases the back pressure of the airflow which reduces the efficiency of the fan as a rad fan. for a good rad fan, you need a strong motor and a good fan blade design. you dont need channeled airflow because once the fan is bolted onto the rad, the air has no where else to go except through the rad. the channeled airflow will not help push the air through the rad any faster because at that point it's a matter of what fan can provide higher static pressure. static pressure is a function of the fan blade design and motor strength.