I have a modem.Due to heating issues i fixed a double cooling fans with that.now i get a small doubt.that is "will the magnet in the fans will affect the modem in anyway?"
thanks in advance.
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No - there is nothing in the modem that would be affected by anything other than a powerfull (and changing) field. The magnet in the fan motor is tiny, it's hard to detect even with a magnetic field sensor!
But if a modem is overheating it's probably a fault in the modem, or you need to place it somewhere cooler or with better airflow. If the modem is inside a rack/enclosure then adding a cooling pad is only going to make it worse