This document proposes and evaluates three energy-efficient power-saving policies for cloud computing systems: (1) alternating a server between idle and sleep modes, (2) allowing repeated sleep periods for a server, and (3) allowing a server to stay in sleep mode only once per cycle. It builds queuing models of these policies and compares their performance to a typical system without power-saving. Through simulation, it finds the proposed policies can reduce costs and improve response times compared to the typical system, while still meeting service level agreements.