Question 3pin/4pin case fans and motherboard pwm/dc

Dec 17, 2020
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Hi,

Im a little bit confused what case fans I should get for my Fractal Design Define S2 case and MSI B550 Carbon wifi motherboard.
The motherboard has 4pin case fan headers,
so should I:
1.Go with 4pin case fans, that are a little pricier to be able to control the fan speed in bios with PWM options.
2.Go with 3 pin case fans that are cheaper, like Fractal Design Silent Series R3 and just have them be on full speed all the time ?
3.Or can I change the 3pin fan header to 4pin fan header with the adapter that comes along like in Noctua NF-A14 ULN, or buy it separately for any other 3 pin case fan ?
4.I'm not sure if I can control the 3pin fans in bios with my motherboard, in the manual it says ''You can switch between PWM mode and DC mode and adjust fan speed in BIOS''. So would I use the DC mode to change the voltage with the case fans, to have the same effect like PWM?
5.The S2 case also has a 3/4pin fan hub that connects to motherboard that controls all the fans, would this be better than connecting them to motherboard ?
 

Paperdoc

Glorious
Ambassador
The three fans supplied with that case are of the 3-pin design. All the mobo headers (use the four SYS_FAN headers for the case ventilation fans) have 4 pins, as you say. That is only because all those headers CAN be configured to control either type of fan, so you can plug in either type. You've seen the info on the mobo manual, p.25. What that means is that for EACH SYS_FAN header (you configure each separately) you can set whether the header uses PWM Mode (for 4-pin fans) or DC Mode - you need this one for your 3-pin fans. With that many headers you can simply plug each fan into its own SYS_FAN header. When you have set all of them to DC Mode in BIOS Setup, remember to use Esc back to Main Menu, then F10 to get to the Exit Menu and choose to SAVE and EXIT to save your settings and reboot.

I suggest you ignore the fan Hub included with the case. You dont need it - you have enough fan headers on your mobo. Moreover, some Hubs can NOT control the speed of 3-pin fans. Use the mobo CPU_FAN1 (and maybe the PUMP_FAN1 if you need it) for your CPU cooler equipment.
 

Prad_Bitt

Notable
Jul 4, 2020
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The three fans supplied with that case are of the 3-pin design. All the mobo headers (use the four SYS_FAN headers for the case ventilation fans) have 4 pins, as you say. That is only because all those headers CAN be configured to control either type of fan, so you can plug in either type. You've seen the info on the mobo manual, p.25. What that means is that for EACH SYS_FAN header (you configure each separately) you can set whether the header uses PWM Mode (for 4-pin fans) or DC Mode - you need this one for your 3-pin fans. With that many headers you can simply plug each fan into its own SYS_FAN header. When you have set all of them to DC Mode in BIOS Setup, remember to use Esc back to Main Menu, then F10 to get to the Exit Menu and choose to SAVE and EXIT to save your settings and reboot.

I suggest you ignore the fan Hub included with the case. You dont need it - you have enough fan headers on your mobo. Moreover, some Hubs can NOT control the speed of 3-pin fans. Use the mobo CPU_FAN1 (and maybe the PUMP_FAN1 if you need it) for your CPU cooler equipment.
+1 for this. This is why I don't have a fan hub. I have only 2 PWM out of 6 total fans in my case including the CPU fan. They're all connected in individual fan headers on the mobo
 

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