The upper power supply delivers the 12 Volts for the modems cards. When the case is closed (and you must close it for the total airflow passing the complete unit,) there is no way for the very hot air to leave the upper power supply, esspecially without any "help".

What we suggest is to add a little fan inside the airflow but directed into the power supply units. It is a must, that you make (drill) a lot of wholes in the metal case of the MAX directly over the power supply.

The hot air must have an outlet. It must flow. If these wholes are to big in diameter, there is the danger, that another person can touch the high voltage components of the electronic parts. So take care, that there is any kind of a grid or grill installed. You must protect other people.