PWM fan no spinning

Plouto

New member
Hello,

I have a Noctua NF-F12 PPC 2000 PWM fan installed as exhaust on my rig. I have connected it's power 4-pin cable on my maximus VIII Ranger cha_fan1 header. What I have noticed is that when I boot my PC the fan does not start spinning unless I unplug it and re-plug it. The it starts spinning at full speed until I use the Asus Fan Xpert to reduse the RPM.

I have tried to connect it at the water_pump header and the same thing happens. Also tried to modify it via BIOS but no luck. The motherboard sees the fan but for some reason it is like it cannot apply fix RPM or voltage.

It is only happening when I power on my PC not on re-boot.

Any ideas?

Thanks



 
Is the cha_fan1 header set to spin the fan at a set temp? If so what temp?
Each header can be set in the BIOS to react to a specific environmental variable such as CPU/Chipset/Case temp.
 
Is the cha_fan1 header set to spin the fan at a set temp? If so what temp?
Each header can be set in the BIOS to react to a specific environmental variable such as CPU/Chipset/Case temp.


Yes the cha_fan 1 is set up to spin at 40% utilization from 0 to 30 degrees celsius based on CPU temperature.

I also have other 3 120mm 1500rpm fans connected to cha_fan 2-3-4 and they are working correctly.
 
Sounds like it it a power requirement issue for fan start up.

Have you tried at 50%, without knowing what voltage the fan requires to start up I couldn't say exactly what % it would need.
 
Is the cha_fan1 header set to spin the fan at a set temp? If so what temp?
Each header can be set in the BIOS to react to a specific environmental variable such as CPU/Chipset/Case temp.


The fan requires 12 V. But I cannot define if the motherboard headers are supplying this power when the PC starts. Do you mean that this is dependant on the actual startup utilization preset for the fan?
 
Even when fans will spin at say 20% speed, they quite often need a "Initial voltage" to get them running before they can reduce to that speed. Does the fan work if set to 100% on that header? if so start to drop it down to see if that is the issue.
 
Even when fans will spin at say 20% speed, they quite often need a "Initial voltage" to get them running before they can reduce to that speed. Does the fan work if set to 100% on that header? if so start to drop it down to see if that is the issue.

I found this in a forum:

Note that if using the PWM fan control feature, do not attempt to add in the enclosed
low noise cable/adapter as the voltage drop prevents fan startup. Not an issue with non PWM control (on/off in your BIOS)

What does he mean by the enclosed low/noise cable adapter?
The fan came just with four screws and a 4-pin power connector.
 
Set the header to 100% just to make sure the fan works, if it doesn't test the header with another fan. If the fan wasn't receiving a PWM signal it would run at 100% so it sounds more like it's not getting power for some reason.

JR
 
The fan only starts after cold rebbot if connected to CPU_OPT header and only then. The thing is that the RPM is really low and it seems that there is no way to control the fan.
 
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