When I turned on my PC, it suddenly displayed a CPU fan speed warning. I unplugged and reconnected the CPU fan cable, but the message still appears. The system uses a NZXT 360 mm liquid cooler with a display, and the fans appear to be spinning. The BIOS reports N/A for the CPU fan speed, and the CPU temperature is reaching about 80°C. What should I check or do for now?
2 Answers
First check the BIOS hardware-monitoring screen and see whether the CPU_FAN header reports any RPM. With an AIO, the radiator fans may spin while the pump or its tachometer signal is connected somewhere else. Make sure the pump’s three- or four-pin tach cable is connected to CPU_FAN, CPU_OPT, or the header recommended by NZXT, and verify that the pump itself is running. You can raise the minimum CPU-fan threshold in BIOS if the signal is just below the warning level, but do not ignore the warning if the pump is not working.
Since the BIOS shows N/A even though the fans spin, the fan cable may be connected to a hub or fan controller that is not sending an RPM signal to the motherboard. Check the cooler’s wiring and its manual, then inspect the pump speed and CPU temperature in BIOS. Avoid heavy use until you confirm the pump is operating; 80°C may be acceptable under load, but it is worth checking the cooler mounting, pump connection, and thermal paste if temperatures are high at idle.
The cooler is a NZXT 360 mm AIO with a small display. The fans are spinning, but the BIOS still shows N/A for CPU_FAN, and the CPU reaches around 80°C. I will check whether the pump tach cable is connected to the correct motherboard header.