My fan doesn’t spin when I start up the PC, is it faulty?
If you've connected the fan directly (or using the supplied Low-Noise or Ultra-Low-Noise-Adaptors) to your motherboard, it's possible that the motherboard's automatic fan controller doesn't provide the required starting voltage due to the low CPU temperature. Please verify whether the fan starts spinning at higher CPU temperatures, remove any Low-Noise or Ultra-Low-Noise Adaptors or deactivate your motherboard's automatic fan controller in the BIOS.
I get a CPU fan error although the fan is running, is it faulty?
Some motherboards display a CPU fan error when the fan speed falls below a certain threshold, e.g. 900rpm. If you want to run the fan below this speed (e.g. using the supplied U.L.N.A.), please adjust the threshold in the BIOS or disable CPU fan error warning.
My Noctua PWM fan starts to spin when the PC boots but then stops, is it faulty?
Some motherboards feature 4-pin fan headers that don’t use a PWM signal on Pin 4 to control the fan speed, but rather reduce the voltage on Pin 2 (like a standard 3-pin fan header). In this case, the motherboard may reduce the voltage so much that the fan stops. Please refer to your motherboard manual to check whether your motherboard has 4-pin fan headers that control the fan speed by reducing voltage on Pin 2 rather than by changing the PWM duty cycle on Pin 4:
Note that motherboard manufacturers use different terms to indicate that Pin 4 is not being used for PWM control (e.g. “+5V”, “VCC” or “NC”), but if one of these terms is used, you can be sure that the fan header does not support PWM. If Pin 4 is described as “Speed Control” or “PWM” or the like, you can be sure that the fan header supports PWM.
Unfortunately, the description of Pin 2 is not always a clear indication, as some manufacturers use terms such as “Fan PWR” or “Power” for both types of fan headers. However, if Pin 2 is described as “Speed Control”, you can also be sure that the fan header does not support PWM based speed control. If Pin 2 is described as “+12V”, this is a clear indication that the fan header supports PWM.
Please also note that in some cases, the descriptions of the pin layouts in the motherboard manuals may not be correct and some models actually allow you to switch the fan headers from voltage control mode to PWM control mode in the BIOS even though the pin descriptions do not indicate PWM support. We thus recommend to look for these options in the BIOS before taking other measures. In case of doubt, please contact your motherboard manufacturer.
To resolve the issue, you can:
Choose a higher fan speed profile in the BIOS (e.g. „normal“ instead of „silent“, etc.) or deactivate automatic fan speed control and use a Low-Noise Adaptor instead.
Use the motherboard‘s fan speed control software or 3rd party tools like Speedfan to regulate the fan speed. Unlike BIOS based fan speed control, the supplied software usually checks whether the fan has stopped and increases voltage accordingly or at least offers more options to set up the fan properly.
If your motherboard features other 4-pin fan headers that use PWM for speed control, you can run multiple fans from these headers using Y-split cables. Make sure not to exceed the specified maximum power draw of the fan headers (usually 10-12W) though.
I'm experiencing fan speed issues with my motherboard from Supermicro, what can I do?The BIOS of many motherboard models from Supermicro expects a certain minimum fan speed (usually 600 or 700rpm), which is higher than the minimum fan speed that can be achieved with Noctua's PWM fan models. The BIOS may interpret the low minimum RPM of Noctua fans as a fan error and thus try to run the fan at 100% for a short period before going back to automatic control. This can result in oscillating fan speeds and fan speed warnings in the BIOS or the fan management console.
Unfortunately, there is usually no option to set a lower minimum value in the BIOS that would suit the low minimum speed of Noctua PWM fans. The issue can thus only be resolved by either disabling automatic fan speed control in BIOS, which will cause the fans to run at a constant speed, by using 3rd party tools like IPMItool orIPMIutil, or by requesting a modified BIOS file from Supermicro, which takes the minimum fan speed of Noctua fans into account (charges might apply). Please note that any modifications performed with 3rd party tools are done at your own risk and that Noctua cannot be held responsible for any possible issues