Question Is it possible for my mobo to control my 3 pin fans through splitters?

Oct 29, 2020
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MOBO: ROG Strix b450-F Gaming
Fans: Rosewill 120mm, Rosewill 140mm
I have 6 fans total, and my motherboard has 3 fan headers. I want to connect 2 fans to each of my fan headers with splitters. I've been trying to research if controlling a 3 pin fan is possible, but I can't find the answer for my specific motherboard. Can my motherboard control 3 pin fans? If so, can it control multiple 3 pin fans through a splitter? What splitter should I use?
 

Darkbreeze

Retired Mod
Yes, it will. You simply need to choose the DC control option in the BIOS under the Q-fan control section.

I would not use more than two fans per header. Three could technically be ok, but it's pushing things.

Keep in mind as well that you also have a CPU_OPT and AIO_Pump headers as well, and quite often those headers are individually configurable as well, including the option to change the source control (CPU, motherboard, VRM, GPU, etc.) and the DC or PWM control type, so you MIGHT also be able to use those headers to run additional chassis fans but you will have to explore that option through trial and error because many boards do this differently, even from the same brand on the same chipset.

In some cases the CPU_OPT can ONLY be controlled via the same options that the CPU_FAN is using, and on others it can be configured independently. On some the AIO_PUMP header can ONLY be run at full speed, while on others, again, it can be configured with a custom profile.
 
Oct 29, 2020
2
0
10
0
Yes, it will. You simply need to choose the DC control option in the BIOS under the Q-fan control section.

I would not use more than two fans per header. Three could technically be ok, but it's pushing things.

Keep in mind as well that you also have a CPU_OPT and AIO_Pump headers as well, and quite often those headers are individually configurable as well, including the option to change the source control (CPU, motherboard, VRM, GPU, etc.) and the DC or PWM control type, so you MIGHT also be able to use those headers to run additional chassis fans but you will have to explore that option through trial and error because many boards do this differently, even from the same brand on the same chipset.

In some cases the CPU_OPT can ONLY be controlled via the same options that the CPU_FAN is using, and on others it can be configured independently. On some the AIO_PUMP header can ONLY be run at full speed, while on others, again, it can be configured with a custom profile.
So will any 3 pin splitter work? Both fans on one header can be controlled?
 

Paperdoc

Glorious
Ambassador
It can be hard to find 3-pin Spltters, but you do no need them. A 4-pin Splitter also will work. When you plug in your 3-pin fans, it simply will not use Pin #4. It does NOT need a connection to that pin.

A Splitter actually is the ONLY way to connect 3-pin fans together to a single header. It ensures that all of its fans gets exactly the same signals from the header, and that includes a VARIABLE voltage supply from Pin #2. That is the only way to control the speed of a 3-pin fan. (A fan HUB is a very different device that can only control the speeds of 4-pin fans because the method of control (the signals from the header) are different.)

As Darkbreeze said above, you can set your mobo's fan headers to do control properly. See your manual p. 3-8. For EACH header you can select at upper right to use DC Mode to control 3-pin fans.
 

Darkbreeze

Retired Mod
It can be hard to find 3-pin Spltters, but you do no need them. A 4-pin Splitter also will work. When you plug in your 3-pin fans, it simply will not use Pin #4. It does NOT need a connection to that pin.

A Splitter actually is the ONLY way to connect 3-pin fans together to a single header. It ensures that all of its fans gets exactly the same signals from the header, and that includes a VARIABLE voltage supply from Pin #2. That is the only way to control the speed of a 3-pin fan. (A fan HUB is a very different device that can only control the speeds of 4-pin fans because the method of control (the signals from the header) are different.)

As Darkbreeze said above, you can set your mobo's fan headers to do control properly. See your manual p. 3-8. For EACH header you can select at upper right to use DC Mode to control 3-pin fans.
Well, there is of course a third option which is to use something like the NZXT Grid+ v2 or v3, which WILL provide control for both 3 and 4 pin fans. But that's a much more expensive option AND not all or even most of the fan controllers out there will even DO variable speed control for 3 pin fans. Most of them, like you say, will only allow that kind of control for 4 pin fans. There are a couple like the Grid+ and I believe the Corsair commander as well, that will handle DC controlled fans in this way as well.
 

Paperdoc

Glorious
Ambassador
I agree. Another new model of fan Hub, the Phanteks Universal Fan Controller, model PH-PWHUB_02, does this well. It can accept input signals from either DC Mode or PWM Mode headers, and has outputs for both 4-pin PWM fans and 3-pin Voltage-Controlled fans. I also agree that, in this particular case, OP does not need that complexity and cost.
 
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