My PWM fan regularly stops spinning – is it defective?

No, the fan is not defective. Thanks to the new motor technology, our new PWM fans come with the so-called 0 dB mode. If the PWM signal falls below 5%, the fan stops and is therefore completely silent.

If the operating load of the computer increases again and more cooling is necessary, the fan is informed via PWM and starts again. This happens fully automatically. 
/