PWM Fan - Plug into CPU Connector with a Splitter?

[Alan G]

I just finished a mITX build to run my television under Windows 10.  I bought the MSI B460I MoBo which is pretty nice and the build was easy.  However, it only has three fan connectors on it.  One is for the CPU, one for a Pump Fan and the third for System Fan.  The System Fan slot is not power managed.  The Pump Fan is power managed and rated at 3A or 36 Watts.  I'm not sure whether I can plug the case fan (PWM Noctua 14 inch)  into that slot because of the higher current possibility or whether the fan will just draw what it needs.  The other possibility is to use a splitter on the CPU fan slot.  I don't do anything with this CPU other than streaming and cable TV viewing so I expect and want the fans to run as slow and quiet as possible.  I prefer a PWM solution rather than controlling the system fan by voltage in the BIOS.  Which of the approaches is best??

 

TIA

[SupaKomputa]

Get a pwm fan hub. It will use molex / sata power connector and the pwm header so you can still use pwm control.

[Alan G]

2 minutes ago, SupaKomputa said:

Get a pwm fan hub. It will use molex / sata power connector and the pwm header so you can still use pwm control.

@SupaKomputaI only have one system fan in a Fractal Design Core 500 case.  I replaced the Fractal fan with a Noctua.  Right now it's plugged into the system fan connctor and running at full speed.  I just want to know if I can plug it into the 3A pump fan slot which is PWM without issue. 

[SupaKomputa]

Fan header usually rated at 1A, so using 3A is a no no.
Check the manual for maximum amperage, if it not listed, better safe than sorry and assume it just 1A.

Get this instead, it using the power from molex but having the PWM from the header.

Google molex pwm fan adapter / controller.

[Alan G]

It's rated 3A and also uses a different sensor.  I'll just use the Noctua low noise adapter that will lower the max fan speed and set up a fan curve in the BIOS which should be pretty simple to do.  I don't know why MSI doesn't just have all PWM connectors.  Normally I use Gigabyte boards for mITX builds but they don't have one in this category that is available.

 

@SupaKomputa  thanks for the comments!!!

[SupaKomputa]

Ok, so the pump header is 3A, is that what you're saying?

Yes you can plug lower amperage fan in that header, but not higher.

6 minutes ago, Alan G said:

uses a different sensor

PWM is the same for pump or fan.

4 pins are all pwm.

[Alan G]

@SupaKomputa correct, the pump header is 3A and PWM, the other system fan header is rated 1A and not PWM.  I'll plug it in to the pump fan header and see what happens.

[SupaKomputa]

You can still use PWM fan in DC mode, it will just work in different way.

PWM the voltage is constant, you control the fan speed by sending a signal.

DC mode controls the fan by controlling the voltage, usually from 40%.

You can plug DC fan (3 pins) in PWM (4pins) vice versa.

You can control both mode from bios.

[Alan G]

It turns out that smart fan control is not enabled by default in the PWM header.  The case fan was way too loud when I set things up five days ago.  This is how I found out that the Sys Fan header on this MoBo is not power managed.  I have it now plugged into the Pump Fan header and enabled smart fan in the BIOS.  It's now running at about 600 RPM as opposed to full speed of 1200 (with the low noise adapter) and it's now quiet.  ASUS boards that I've used had PWM enabled by default. 

 

Thanks for the comments on this @SupaKomputa .  The problem is now solved.