What is located on the bottom left corner of the motherboard, containing space for 10 pins but only using 9 pins?

The component commonly found in the bottom left corner of the motherboard that features 10 pins, while only utilizing 9 of those pins, is the audio header port. This port is specifically designed for connecting the front panel audio jacks, allowing users to connect headphones and microphones directly to the front of the case for convenience.

Typically, the audio header port adheres to the standard arrangement where one pin serves as a keying notch or is designated as a ground, which is why only 9 pins are actively used in the connection. This configuration enables the motherboard to accommodate audio input and output signals without interference.

In contrast, other components such as the CPU power connector primarily deal with powering the processor and are located near the CPU socket, while the USB header ports, which are used for internal USB connections, are arranged differently on the motherboard. The power LED connector is often found at the front panel header area but has a different pin arrangement and purpose, being dedicated to indicating the power state of the system rather than handling audio signals.