A technician replaced a failed PBU on a high-end workstation PC. Now, the PC fails to POST and does not stay turned on for more than five seconds. Which of the following power connections was most likely forgotten during installation?

The 5V connection is typically used for powering components like USB ports or low-power devices within the PC. However, it is not the primary power input necessary for the entire system to operate. The absence of a 5V connection would not cause the PC to fail to POST, as the system requires a higher voltage to power the motherboard and other critical components.

There is no standard 11V power connection in typical PC power supplies. Most power supplies operate on standard voltages, such as 3.3V, 5V, 12V, and the main AC input of 120V or 220V. Therefore, the absence of an 11V connection is irrelevant and would not cause the symptoms described.

The 220V connection serves as the primary input in regions that use this higher voltage standard. While it could also cause a failure to POST if not connected, it is not the correct answer for a technician in a region that uses 120V. Thus, it does not address the specific likely oversight in the context of the question.