You can press the "F 1" key on the keyboard to enter the "UEFI BIOS Interface" to check the fan connection status, as shown in the following figure:
"CPU fan" means "N/A" is not connected, "CHA FAN" means that CPU fan is not connected and chassis fan is connected.
Please check whether the fan on the motherboard is connected to the "CPU Fan" interface when the power is off, and check whether the problem is solved after the fan is connected to the correct interface. (Note: Please be sure to turn off the power. )