3 pin case fan to 4 pin mobo - how?

i know nothing · 15 Apr 2020 at 09:30

I bought a Fractal Design Define S Midi Tower case from OCUK. The two pre-installed fans have a connector that has 3 pins.

I'm looking to connect those two chassis fans to my MSI B450 motherboard, which has 4 pin connectors for system (chassis) fans.

How do I go about this? Do I need an adaptor?

Alex h · 15 Apr 2020 at 09:39

i know nothing said:
I bought a Fractal Design Define S Midi Tower case from OCUK. The two pre-installed fans have a connector that has 3 pins.

I'm looking to connect those two chassis fans to my MSI B450 motherboard, which has 4 pin connectors for system (chassis) fans.

How do I go about this? Do I need an adaptor?

No you can put them to the 4 pin connector on board you just loose the pwm which is the 4th pin to control fan speed from motherboard someone might be able to explain this better than me but you'll be fine connecting they'll just run at full speed

i know nothing · 15 Apr 2020 at 10:36

alex h said:
No you can put them to the 4 pin connector on board you just loose the pwm which is the 4th pin to control fan speed from motherboard someone might be able to explain this better than me but you'll be fine connecting they'll just run at full speed

Ahhh okay. I note the motherboard has a bit of plastic which would orientate the connectors to the left, I'm guessing that would make Pin 1 mate with Pin 1 on the fan connector?

Mcnumpty2323 · 15 Apr 2020 at 10:40

i know nothing said:
Ahhh okay. I note the motherboard has a bit of plastic which would orientate the connectors to the left, I'm guessing that would make Pin 1 mate with Pin 1 on the fan connector?

Yeah there's a groove on the fan connector that lines up with that bit of plastic
If your motherboard supports voltage control as well as pwm you can still adjust fan speed

i know nothing · 15 Apr 2020 at 11:09

Fantastic!

Thanks Guys, all connected. :cool:

EsaT · 15 Apr 2020 at 11:14

Pretty much any motherboard should support voltage control.
That actually used to be the only available control method and it wasn't until in last few years when all motherboards got genuine PWM control signal added.

Though there might be still some older and lower end board or two, whose "PWM" mode is PWM chopping of 12V.

alexakasloth · 15 Apr 2020 at 12:01

When you go into the MSI bios there will be a drop down menu on each fan header, it may well automatically sense it is 3 pin instead of PWM but you can change it to be sure and adjust from there.

MSIUK Support · 20 Apr 2020 at 14:22

To set up fan control for 3 pin fans, select DC mode in the hardware monitor within the BIOS and adjust the curve accordingly.

For GSE-Lite BIOS, you input voltage values (such as 1200 for max fan speed) since there is no curve to adjust.