[SOLVED] CPU fan won’t work in intended port on motherboard.

[BecauseJohn]

When i plug my new CPU fan into the CPU fan slot on motherboard the fan doesn't work. But if i switch the CPU fan with a CHA fan port it works and boots fine. Fan pins look fine. And when a case fan is attached it works. What could be causing my issue and how can i fix it?

I have also tried adjusting settings in my BIOS for fan types, I have also changed the fan speed switch on the cooling tower and nothing works. When I start the pc the fan will run for a second then stop and give me an error screen saying no fan detected. I have checked all connections and nothing seems to be out of place or loose.

Specs are: Cpu - Ryzen 3800x Cooler - prism tower cooler (stock with cpu) Gpu - rtx 2070 Power supply - EVGA 700w Bronze Motherboard - Asus ROG Strix b450-f gaming (updated to support Modern AMD CPUs) 16gb ram - Corsair vengeance OS - Windows 10 64bit

 

[CountMike]

When i plug my new CPU fan into the CPU fan slot on motherboard the fan doesn't work. But if i switch the CPU fan with a CHA fan port it works and boots fine. Fan pins look fine. And when a case fan is attached it works. What could be causing my issue and how can i fix it?

I have also tried adjusting settings in my BIOS for fan types, I have also changed the fan speed switch on the cooling tower and nothing works. When I start the pc the fan will run for a second then stop and give me an error screen saying no fan detected. I have checked all connections and nothing seems to be out of place or loose.

Specs are: Cpu - Ryzen 3800x Cooler - prism tower cooler (stock with cpu) Gpu - rtx 2070 Power supply - EVGA 700w Bronze Motherboard - Asus ROG Strix b450-f gaming (updated to support Modern AMD CPUs) 16gb ram - Corsair vengeance OS - Windows 10 64bit

There is an Low-High speed switch on the cooler, see what it's set at.

 

[BecauseJohn]

There is an Low-High speed switch on the cooler, see what it's set at.

Checked both. And it still doesn’t work.

 

[geofelt]

Are the fans pwm fans or 3 pin fans?
While usually you can plug a 3 pin fan into a 4 pin header, I have found one motherboard that did not work and required a 4 pin fan to work.

 

[BecauseJohn]

The fan is a 4 pin connection. And the motherboard matches.

 

[Paperdoc]

It appears what is happening is that the automatic fan speed control system is set up to send to that fan when the CPU is cool a speed signal that is so low the fan stalls. You can adjust to fix that. But FIRST it is not clear above that you have done this little step. I gather the fan itself has a speed switch on it. That should be set for max speed - in only interferes with the mobo's CPU_FAN control system.

Look in your mobo manual on p. 3-7. First note exactly how the CPU_FAN speed "curve" is set, especially at the low-temp / low-speed end. Next, check at the top right and ensure it is set to use PWM Mode. Then at the bottom, what Profile is chosen? Normally it should be used in Standard Profile; if it is not, try choosing that for starters. But if it is, then you will need to change it by choosing the Manual option. See p. 3-8,, and set the low-speed end to be a higher minimum speed at the lowest temperatures. That way the fan will never get such a low speed control signal that it stalls. You can experiment a bit to find the right minimum. After you make your changes, don't forget to Esc to Main Menu and use the F10 key to get to the Exit Menu (p 3-23), then choose to Save Changes and Reset.