Power is the source of the greatest problems facing microprocessor designers. High-power processors rapidly deplete battery energy. Rapid changes in power consumption result in on-chip voltage fluctuations that bring transient errors. High spatial and temporal power densities bring high temperatures, which result in decreased lifetime reliability. High temperatures also increase leakage power consumption, thereby closing a self-reinforcing powertemperature feedback loop. The effects of increasing power consumption, power variation, and power density are expensive and distasteful. The wages of power are bulky short-lived batteries, huge heatsinks, large on-die capacitors, high server electric bills, and unreliable microprocessors. The only alternative is optimizing microprocessor power consumption, temperature, and reliability. However, this depends on accurate modeling and rapid analysis of properties that span different disciplines and levels, from device physics, to numerical methods, to microarchitectural design. This article surveys the most important problems brought directly and indirectly by power consumption, indicates the relationships among them, explains recent methods of efficiently modeling them, and indicates promising directions in the ongoing fight against power.