Which part of a computer system houses data for long-term storage or acts as temporary overflow storage?

The expansion bus is a communication pathway that connects various components within a computer, such as the CPU, memory, and peripheral devices. It does not store data itself; rather, it facilitates data transfers between components, making it unsuitable for long-term or temporary data storage purposes.

The system clock is responsible for synchronizing the timing of operations within the computer system. It generates clock pulses that coordinate the activities of the CPU and other components, but it does not store data. Its primary function is to ensure that all parts of the computer work in harmony through precise timing.

The motherboard is the main circuit board that houses the CPU, memory, and other essential components. While it provides connectivity and communication paths among these components, it does not serve as a storage device for data. Its role is more about integration and support rather than data retention.