What configuration provides the most reliable power to a rack-mounted computer with a single input cord?

The configuration that provides the most reliable power to a rack-mounted computer with a single input cord is a rack with a static transfer switch. A static transfer switch (STS) is designed to ensure that if the primary power source fails or experiences issues, the load can be transferred instantaneously to a secondary power source without interruption. This automatic switching capability enhances the reliability of power delivery, which is crucial for servers and critical computing systems that cannot afford any downtime.

In scenarios where reliability is paramount, the ability to continuously supply power without even a moment of disruption is essential. The static transfer switch constantly monitors the input power sources and makes transfers seamlessly, which is a significant advantage over other configurations.

While redundant power supplies can offer increased reliability by providing an alternate path for power, in this specific case of having a single input cord, the static transfer switch is more effective at ensuring power continuity, as it can source from various feeds if available. Thus, for a system with a single input and the need for ultimate reliability, utilizing a rack with a static transfer switch would be the best approach.