The modern design of electronic devices is to regulate the temperature using passive or dynamic (a fan) to cool it in times of high digital rates - CPUs working overtime to cool them. A cooling fan does not have to been on 24/7 as this can lead to moving parts failure including dust build up. In an industrial environment where the raid or CPU is number crunching the fan can be scheduled to replace it at set interval.
In a domestic environment the device can be subjected to all sorts of abuse - blocked air to laptops, enclosed TV cabinets. The designer will try to go passive, but if necessary a fan can be switched on or controlled by a circuit temperature sensor.
In the case of my the Humax boxes it does not come on at all even if a blanket is thrown over it.
20 May 2022, 8:53PM