Which component must be installed using screws externally through the PC case?

The power supply is typically installed using screws externally through the PC case because it is designed to be mounted securely in the designated area, often at the top or bottom of the case. The use of screws ensures that the power supply is stable and properly aligned with the case, providing a secure fit that can withstand movement and vibration.

This installation method is important because the power supply generates heat during operation, so proper positioning and mounting help with ventilation, ensuring that heat can dissipate effectively. Additionally, using screws allows for easy replacement if the power supply needs to be upgraded or serviced in the future.

While other components like the motherboard, graphics card, and hard drive also require secure installation, they typically have different mounting methods or locations within the case. For instance, the motherboard is mounted to the case standoffs, the graphics card is usually secured in a PCIe slot and held in place with screws, and hard drives often utilize drive bays or brackets that may not be accessible from outside the case.