Due to the increasing power consumption of data centers, efficient dc power distribution systems have become an important topic in research and industry over the last years. Furthermore the power consumed by data centers is an economic factor, which implies that all parts of the distribution system should be designed to minimize the life cycle cost, i.e. the sum of first cost and the cost of dissipation. This paper analyzes a three-phase buck-type PFC rectifier with integrated active 3rd harmonic current injection for dc distribution systems. Switching frequency, chip area and magnetic components are selected based on a life cycle cost optimization, showing that a peak efficiency of 99% is technically and economically feasible with state-of-the-art SiC MOSFETs and magnetic components. Measurements taken on an 8 kW, 4 kW dm-3 hardware prototype demonstrate the validity and feasibility of the design.