Aaeon SBC-670S Manual page 30

The CPU card has its own buzzer. You can also connect to the
external speaker on your computer chassis. Pin assignments for
SPKER are shown below:
External speaker (SPKER)
Pin
1
2
3
4
You can connect a LED to the connector of IDE LED to indicate
that the HDD is active.
You can connect an external switch to easily reset your computer.
This switch will restart your computer if you hit the RESET switch.
Function
VCC
SPEAKER-
Internal Buzzer
SPEAKER-