Efficiency Analysis of Consolidated vs. Conventional Server Power Architectures Open-source IT systems, like those designed by the Open Compute Project (OCP), are redefining how power is distributed within an IT rack by replacing internal server power supplies with a centralized rack-level power supply. In this paper, we investigate the efficiencies of conventional internal server PSU architectures and centralized rack-level PSU architectures (12VDC and 48VDC). While many believe that consolidating power supplies leads to significant efficiency gains, we found otherwise. With best-in-class components, the consolidated 12VDC rack-level PSU architecture provides a small incremental energy efficiency improvement over the conventional architecture. And consolidating at 48VDC provides another small incremental energy efficiency improvement over 12VDC.