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[SOLVED] 2 pin fan header -possible to use a splitter?

Assaf Patishi

Reputable
Jan 11, 2017
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Hi,
I have a case with fan controller which has three 2-pin headers (for 3 fans). I want to connect 4 fans to it, can I simply use a splitter for one of the headers?
I didn't mention, the fan controller gets power from sata power.
I just want to be sure that it's ok.
Thx.
 

Paperdoc

Glorious
Ambassador
Grone said, "Ok, the only difference is that the fan speed controller can't get feedback of fan RPM and thus the fan speed cannot be controlled, you can probably only either have it fully on or fully off. " That is wrong. No fan speed control system actually uses the real measured fan speed to control the fan speed. (That speed signal IS used by mobo headers to detect fan FAILURE, and to provide info to the user.) A mobo header simply tracks the temperature of an item cooled by the fan, and adjusts the fan speed to keep that temp on target. The adjustment is simply the VOLTAGE supplied to a 3-pin fan, or the PWM speed control signal supplied to a 4-pin fan, but that output signal is NOT dependent on the actual speed that results. In your case, OP, the adjustment is made solely by YOU, when you choose which speed setting manually on the case's control buttons, and the ONLY thing that does is change the VOLTAGE sent out of the 2-pin connector on the control module. The two pins are the + DCV and Ground connections to the fan.

That mechanism will work to change the speed of either a 3-pin or a 4-pin fan. It is quite reasonable to assume that the output capacity of that controller module IS large enough to connect two normal case fans to it via a Splitter. The real question is whether the pin configuration is spaced so that you CAN make the connection. IF the fans you are talking about have standard fan connectors on the end of their wires, then the controller was made to match that and you CAN go ahead with your plan. But if the fans are non-standard and came with the case, is is POSSIBLE (not for sure) the pin layout may not match (either in electrical function, or in spacing) a normal case fan and you might have a small problem in making the connection.
 

Assaf Patishi

Reputable
Jan 11, 2017
50
0
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It is actually 2-pin headers..not 3. I am not sure if 2 pin header can supply enough voltage for 2 fans.
I know that with normal 3 or 4 pin header it's not a problem to connect 2 fans, even if it is coming from the motherboard (and not straight from the psu), and in my case the fan controller is fed by sata power so the problem is not with it not having enough juice, but I'm more worried about the 2-pin not good enough for a fan splitter (with 4-pin headers).
 

Assaf Patishi

Reputable
Jan 11, 2017
50
0
4,540
1
Ok, the only difference is that the fan speed controller can't get feedback of fan RPM and thus the fan speed cannot be controlled, you can probably only either have it fully on or fully off.
it has 3 speeds: low, medium and full speed. one pin is probably for the voltage and I don't know what is the second pin for. But the question still remains..is this 2-pin header can support two fans at once.
I guess I will find out today when I'll install the fans.

I'm actually talking about the Phanteks P400A (non-rgb) that comes with a fan controller. This fan controller gets power directly form sata and have 3 headers for fans (for a total of 3 fans if you don't use splitters). because I want to connect 4 fans to it, I'll have to use a splitter on one of the headers. But I'm not sure if it will work
 

Assaf Patishi

Reputable
Jan 11, 2017
50
0
4,540
1
Well, I can confirm that it works! You can connect 2 fans to one header to the controller on the phanteks P400A. I just used a fan splitter that I got with a noctua fan I got laying around.
 

Paperdoc

Glorious
Ambassador
Grone said, "Ok, the only difference is that the fan speed controller can't get feedback of fan RPM and thus the fan speed cannot be controlled, you can probably only either have it fully on or fully off. " That is wrong. No fan speed control system actually uses the real measured fan speed to control the fan speed. (That speed signal IS used by mobo headers to detect fan FAILURE, and to provide info to the user.) A mobo header simply tracks the temperature of an item cooled by the fan, and adjusts the fan speed to keep that temp on target. The adjustment is simply the VOLTAGE supplied to a 3-pin fan, or the PWM speed control signal supplied to a 4-pin fan, but that output signal is NOT dependent on the actual speed that results. In your case, OP, the adjustment is made solely by YOU, when you choose which speed setting manually on the case's control buttons, and the ONLY thing that does is change the VOLTAGE sent out of the 2-pin connector on the control module. The two pins are the + DCV and Ground connections to the fan.

That mechanism will work to change the speed of either a 3-pin or a 4-pin fan. It is quite reasonable to assume that the output capacity of that controller module IS large enough to connect two normal case fans to it via a Splitter. The real question is whether the pin configuration is spaced so that you CAN make the connection. IF the fans you are talking about have standard fan connectors on the end of their wires, then the controller was made to match that and you CAN go ahead with your plan. But if the fans are non-standard and came with the case, is is POSSIBLE (not for sure) the pin layout may not match (either in electrical function, or in spacing) a normal case fan and you might have a small problem in making the connection.
 

Paperdoc

Glorious
Ambassador
OP, thanks for Best Answer.

Grobe, sorry I typo'd your name wrong. I've never used Speedfan, so I am not aware it can be used to control to an actual speed target - I'll take your word for that. I was speaking of the systems used by mobo headers and their BIOS software tools. Neither of those actually tries to achieve a target speed, nor do they care. The older system basically did this: here's 9.37 Volts, so run with that. (And whatever speed that produces is OK, until the BIOS decides that the temperature measurement has changed, and sends out a new Voltage.) The newer PWM system does it this way: I want you to run with full power on for 47% of the time, whatever speed that produces. Etc. The PWM signal is an on-and-off signal cyclcling at about 25KHz with varying "% On". It does not specify any speed, but you could create a circuit to scale that from 30 to 100% On into a speed target of, say, 400 to 2,000 RPM, and then create a speed control circuit to drive the motor (using what method?) to meet that target, based on a speed feedback signal. That is more complex than what a mobo BIOS does. Oh, and you'd have to arrange for the scaling system to be adaptable to different fans with different speed range capabilities.
 

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