AB350 Gaming ITX CHA_FAN1 not working

wino wrote: The CHA_FAN1 header works - that's a fact :) The other fan connected to it works and the water pump connected to it also works: "What's more, the "W_PUMP" mode is IMHO really useless because it pumps at full speed all the time" - these are your words ;) So I suggest connecting the water pump to CHA_FAN1 with CHA_FAN1 mode (not W_PUMP due to your preference) and the BeQuiet Silent Wings 3 fan to CHA_FAN2. If this does not help - try other settings (silent mode, full speed mode, customize mode, etc.) because everything indicates that the connector is working properly. You can also try connecting one fan at a time to find the cause.

Thank you very much for your message.

While your suggestion to connect my water pump to CHA_FAN1 is a good idea (although not easy for me because of how difficult CHA_FAN2 is to get to since I have installed a full motherboard waterblock), I would like to share a finding I just made which seems very odd to me :

So my motherboard is set to PWM Mode for CPU_FAN and for CHA_FAN1.
However, I pulled my multemeter and measured :
12V between the yellow and the black wire of a fan on CPU_FAN
Only 5.85V (let's call it 6V) between the same wires of the same fan when I connect it to CHA_FAN1.

That seems really weird to me, and makes me think my motherboard is perhaps kind of mixing PWM and DC modes... What do you think?

Okay, I tried different settings and here are the conclusions :)

When I set the maximum power on CHA_FAN1, the voltage increases to 12V. Previously, I had it set to 40%, so the voltage was only 6V.

I always thought that in the case of 4-pin fans, the 4th pin is responsible for controlling the fan speed. It seems that (at least on our motherboard) the speed is controlled by the voltage applied to pin 2.

wino wrote: Okay, I tried different settings and here are the conclusions :) When I set the maximum power on CHA_FAN1, the voltage increases to 12V. Previously, I had it set to 40%, so the voltage was only 6V. I always thought that in the case of 4-pin fans, the 4th pin is responsible for controlling the fan speed. It seems that (at least on our motherboard) the speed is controlled by the voltage applied to pin 2.

I think you are correct in thinking that in PWM mode the voltage sent to the fan should always be 12V, and the modulation is made through the signal sent through the 4th pin.

So to me our measurements of around only 6 volts between the 2 first pins is a problem: it corresponds to a speed reduction in DC mode, but should not occur in PWM mode.

wino wrote: It seems to me that this is not a bug. CPU_FAN and CHA_FAN2 are headers intended only for PWM (4-PIN) fans. The CHA_FAN1 header is designed for both types of fans - PWM (4-PIN) and DC (3-PIN). That?�s why its behavior is different. Yes, 4-PIN fans will work here, even in PWM mode, but in this case it?�s probably some kind of "legacy" mode. That?�s why, regardless of which mode we set (DC or PWM), the speed is controlled by voltage. Apparently, it can?�t be done any other way if we want a header that can operate in both modes.

I don't see why : set the voltage to 12V and activate the 4th pin with the modulation signal for PWM Mode, or do not activate the 4th pin and modulate the voltage on pin 2 for DC mode. That seems quite straightforward to me.