be quiet! is making these fans in several different models and I have received several of them as well. However, there are some common features that can be lined up. Funny enough, it is actually the PWM fans in the series that make the most noise, but you can't say 'noise' in that sense. Because that's not what I would define the whispering noise they make. Also note that there is a full 3-year warranty on these fans and they are guaranteed a lifetime of 80,000 hours, which is 9 years of nonstop running. The fans are not intended for coolers or radiators, as they cannot deliver a static pressure that is high enough, they are for casing and airflow only.