AAEON EMB-KB1 - Manual (Page 23)

2-15 Chapter 2: Motherboard information
CAUTION: Do not forget to connect the fan cables to the fan connectors.
Insufficient air flow inside the system may damage the motherboard
components. These are not jumpers! Do not place jumper caps on the fan
connectors!
NOTE: The CPU_FAN connector supports a CPU fan of maximum 2A (24 W)
fan power.
2. CPU and chassis fan connectors (4-pin CPU_FAN, 4-pin CHA_FAN)
Connect the fan cables to the fan connectors on the motherboard, ensuring
that the black wire of each cable matches the ground pin of the connector.
EMB-KB1 Fan connectors
CHA_FAN
GND VCC SENSE PWM
CPU_FAN
GND VCC SENSE PWM