5420F switches come with one fixed power supply. You can install an additional power supply for redundancy. 5420M switches do not come with installed power supplies. You can install one or two power supplies. All installed power supplies must blow air in the same direction and must match the airflow direction of the installed fan modules. 5420 Series switches are only available with front-to-back airflow. Many Extreme Networks switches are shipped with an internal power supply that supplies all of the power needed for most switch operations. The internal power supply is fixed on some switches and replaceable on other switches. Other switches, such as the X450-G2 and the X460-G2, require power supplies to be ordered separately. See Power Supplies for Use with Your Switch for supported power supplies.
For installation instructions, see Replace Power Supplies.