A system for delivering direct current power to field replaceable units, further referred to as FRUs, of a computing rack, comprising a power conversion apparatus, wherein the power conversion apparatus comprises: a rectifier comprising: a plurality of input nodes for receiving a respective plurality of mains power supplies; and at least one output node for outputting a DC power supply; and an electrical bypass mechanism comprising: an input node electrically interconnected to the output node of the rectifier; a first output node electrically interconnected to a first power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a second output node electrically interconnected to a second power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a first conductive path electrically connecting the input node and the first output node; characterized by the electrical bypass mechanism comprising a second conductive path electrically interconnectable between a) the input node of the electrical bypass mechanism or the first conductive path, and b) the second output node, whereby the first and second output nodes are configured to output respective DC voltages when the power conversion apparatus receives an input power source, regardless whether that input power source is received from one or more of the plurality of mains power supplies at the input nodes of the rectifier or from one or more DC input power sources (582, 586, 598) connected to the first and/or second output node (562, 566) of the electrical bypass mechanism. a rectifier comprising: a plurality of input nodes for receiving a respective plurality of mains power supplies; and at least one output node for outputting a DC power supply; and a plurality of input nodes for receiving a respective plurality of mains power supplies; and at least one output node for outputting a DC power supply; and an electrical bypass mechanism comprising: an input node electrically interconnected to the output node of the rectifier; a first output node electrically interconnected to a first power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a second output node electrically interconnected to a second power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a first conductive path electrically connecting the input node and the first output node; characterized by the electrical bypass mechanism comprising an input node electrically interconnected to the output node of the rectifier; a first output node electrically interconnected to a first power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a second output node electrically interconnected to a second power distribution unit configured to deliver DC power to a plurality of FRUs within a computing rack; a first conductive path electrically connecting the input node and the first output node; characterized by the electrical bypass mechanism comprising a second conductive path electrically interconnectable between a) the input node of the electrical bypass mechanism or the first conductive path, and b) the second output node, whereby the first and second output nodes are configured to output respective DC voltages when the power conversion apparatus receives an input power source, regardless whether that input power source is received from one or more of the plurality of mains power supplies at the input nodes of the rectifier or from one or more DC input power sources (582, 586, 598) connected to the first and/or second output node (562, 566) of the electrical bypass mechanism.