There is really no resource draw and the only type display and such is generally command line telnet on the head. pretty much designed to be operated by remote through Telnet or the Browser interface.
I have servers running in 100 Watt power supplies as they are just a
motherboard, HDD, Power supply, and case with no head.
Servers generally do not use much resources and there is no GUI or a bunch of cards drawing tons of power. Graphics, Accessories, and Windows chews up the resources like crazy as well as the power.
