QuoteThe Acer DustDefender application prevents dust from accumulating inside the system. The fan briefly reverses every 3 hours to flush out dust, enabling the components to stay cool, perform better, and last longer. This application is enabled by default. You can manually run Acer DustDefender via the Acer Quick Access application.
Quelle: http://acer.custhelp.com/app/answers/detail/a_id/35243/~/acer-dustdefender
Ich interpretiere die Aussage aus dem Test so, dass es wohl öfter als alle 3h vorkommt ;)