[SOLVED] "SYS_FAN#" on Mobo has 4 Pins, Connector Cable Has 3 Holes?

[MarsColonist]

Motherboard: MSI B550-A PRO
Case: Be Quiet! Pure Base 500DX

I was trying to get some case fans connected just now and noticed that the connector points I thought I was supposed to use on this motherboard seem to have 4 pins, but the fan connectors appear to only have 3 holes for these pins...

But those connector points on the motherboard, as you can see in the photos -- they are labeled "SYS_FAN" followed by a number... so those should be for case fans, right? It would seem... and yet the hole count doesn't match the pin count, so I suppose I can't/shouldn't try to connect them...?

https://flic.kr/p/2kGvV2Z

View: https://flic.kr/p/2kGvV2Z

https://flic.kr/p/2kGsjii

View: https://flic.kr/p/2kGsjii

https://flic.kr/p/2kGsjhm

View: https://flic.kr/p/2kGsjhm

 

[clutchc]

Yes, you can connect 3-wire fans to the 4-pin header on the motherboard. Most modern boards have the option of either DC (3-wire) or PWM (4-wire) control. If your board doesn't have the option, the fan will simply run at full speed all the time.

The header is 'keyed' so you can only plug it in using the correct set of pins.

 

[MarsColonist]

My PSU has these cables (I think called "molex" ?) that can be used to power case fans also, right?

I remember seeing these on some PCs I built like 10 years ago.... I think. If I wanted to use these to power fans, could I use these instead of the case fan plugins on the motherboard we were talking about? How?

https://flic.kr/p/2kGRH6Q

View: https://flic.kr/p/2kGRH6Q

 

[clutchc]

Yes, with an adapter. But the fan(s) you connect to that Molex connector will always be running at full speed. No harm, but may be noisier than you prefer.