Data server with hot replaceable processing unit modules

A data server having a plurality of hot replaceable processing unit modules. Each module includes a motherboard having plugged therein: a CPU; a main memory; an I/O adapter card, and an interconnect printed board, electrically connected to the motherboard. A backplane has a first connector adapted for coupling to a DC power supply. The interconnect printed circuit board has a DC to DC converter connected to a second connector adapted to mate with the first connector to enable the processing unit module to be hot plugged into, or removed from, the backplane. The backplane has formed thereon a strip transmission line adapted to provide an Ethernet bus for interconnecting a plurality of the modules. A cable management system for a cabinet used to house the module includes at least one vertically extending channel disposed in the cabinet and a fastener adapted to open and enable the a cable to be inserted into the channel and close to retain such cable within the channel. A chassis having a plurality of shelves for supporting electrical modules with a partitioning member adapted for removable insertion onto one of the shelves to accommodate modules with different widths. An I/O adapter card mounting plate, with captive hardware, adapted for securing an array of I/O adapted cards, and honey-combed I/O adapter card filler plate to a case. A method for booting operating system software into a main memory of a processing unit.