Power systems and methods for supplying direct current power to a server rack employ multiple power supply units. A method for supplying direct current power to a server rack includes receiving an alternating current (AC) power input. A first portion of the AC power input is transferred to a first automatic transfer switch (ATS). A first DC power input is generated from the first portion of the AC power input via a first power supply unit (PSU) and transferred to the server rack. A second portion of the AC power input is transferred to a second ATS. A second DC power input is generated from the second portion of the AC power input via a second PSU and transferred to the server rack.