When you see the error message "CPU FAN Error" in POST, it means the system doesn't detect the FAN.
1. Please make sure the CPU FAN is installed on the right position of the motherboard and twist the screws tightly.
2. Ensure that the CPU FAN cable is securely installed to the CPU_FAN connector instead of the CHA_FAN.
3. If you install another brand of CPU FAN with lower revolutions speed, the system may not be able to correctly detect it.You can try to set "CPU Fan Speed Low Limit" to 200 RPM in BIOS configuration.
4. You can set Monitor->CPU FAN Speed to Ignore if you don't want to open the computer case.