Establishing a power profile of power consuming components of computer system configurations for generating electrical ratings, beginning with a default, limited configuration of a computer system and continuing for a number of configurations of the computer system, each configuration including additional power consuming components not included in a previous configuration, where establishing a power profile includes: measuring, for a present configuration, power consumption of the computer system; calculating, in dependence upon the measured power consumption for the present configuration, an estimated power rating for the one or more additional power consuming components; and recording, in a power profile, estimated power ratings for the additional power consuming components, where the number of configurations of the computer system for which power consumption is measured is less than the number of possible configurations of the computer system.