When a technician replaces a video card in a desktop PC, which crucial step did he forget?

When replacing a video card in a desktop PC, it is essential for the technician to disconnect the power cable prior to any component replacement. This step is crucial because it ensures that there is no electrical current flowing through the system while work is being conducted. This not only protects the technician from potential electric shock but also prevents damage to the computer's components, including the new and existing video cards, during the installation process.

The act of disconnecting the power cable forms a fundamental safety protocol in computer hardware maintenance. It reduces the risk of short circuits, electrical shorts, or other failures that could occur if components are handled while powered on.

Additionally, while other steps like opening the case, installing the new card, and reconnecting peripherals are important parts of the installation process, the initial action of cutting power is a safety prerequisite to ensure a secure and safe hardware replacement. Hence, forgetting this step can lead to hazardous situations or component failure.