The input AC Power Factor of a DC power supply has a significant effect on input AC current, and therefore affects system design. since system efficiency and Power Factor can vary significantly as a function of system configuration, analysis of system powering and overall efficiency requires a realistic system model which accommodates the wide variety of modern system designs, re-designs, and upgrades. This paper will discuss the effects of system configuration, Power Factor, and AC Line Power Supply performance on overall system efficiency. A unique system simulator which permits accurate modeling of all known system configurations will be described, along with test data obtained. A simplified method of system design and performance analysis which was developed using the system simulator will be presented.