A power supply unit that obviates the need for an uninterrupted power supply (UPS) for a server in a data center by receiving a DC power from a temporary backup power source. The power supply unit converts AC power received from a power utility service into a DC power for operating one or more motherboards of the server. An AC to DC converter in the power supply unit senses an input AC voltage and activates a DC to DC converter coupled to the temporary backup power source. The DC to DC converter powers the one or more motherboards until a generator serving as an auxiliary AC power source becomes operational. The power supply unit resumes connection to the AC to DC converter after the generator becomes operational.