Surprisingly this switch's PSU converts AC to only 5V. On idle and boot, it only consumes 15W. Of course with SPFs, and more connections, this will probably require more power. To this end, I chose a 50W 12v to 5V converter (others are available, but i thought a wide range was a good idea). There is also enough space inside the case to contain the converter, and a switch to choose either AC of DC power sources.