Do i need to connect my fan to psu if i connect it already to motherboard?

[ken.manguera]

Hi,

Noob question here.
Do i need to connect my fans to the psu if i connect it already to the motherboard?

Mobo: ga-ab350n gaming wifi (2 fan header slot)

I have 6 fans to connect:
4x120mm
1x90mm
1xcpu fan

I have 2 3-way fan header splitter, i already computed the max amp per fan header slot. I just want to be sure if i can control my fan speed using my mobo and if i need extra power using my psu for this.

Thanks!

 

[Kenton82]

The fans that are connected to the MOBO do not need separate power from the PSU as they draw through the board. But if you wish to add some more fans, then a fan controller may be a better idea, although the sort of power draw you will see being used by a case fan is largely negligible! The fan controller however WILL need power from the PSU. I have my cpu fan running at MAX plugged into the CPU fan header, and one on the rear of the case pulgged into the rear chassis fan header. Then i have a further 3 fans, 200mm on the side of the case, 200mm on the front, and a 200mm on the top of the case - plugged into a fan speed controller - which uses a separate feed from the PSU. This all gives me loads of control over my cooling.

Hope this may help.
K

 

[CountMike]

NO !!! Never connect a fan to both sources. If you connect a fan to MB and than into PSU at same time it would send 12v straight into your MB and most probably burn the crap out of it.

 

[Paperdoc]

Normally one would connect ONLY the CPU cooling fan to the CPU_FAN header, and all the case fans to the only SYS_FAN header you have. That is because those two headers should be set to use different temperature sensors as their reference measurement. The CPU_FAN header will us the sensor inside the CPU chip, whereas the SYS_FAN header should be configured to use a sensor on the mobo.

In your case, OP, you have five case fans. You have said you already know the current draws and have calculated the loads for use with your two Splitters, but have not said how you assigned the fans to which headers. I'm guessing you have put at least one of the case fans on the CPU_FAN header (maybe two?) which is not exactly ideal, but it certainly CAN be done that way if the fan loads are OK. I'm also guessing that connecting all five case fans to the single SYS_FAN header would violate the load limits there. So probably you have arrived at your best option already.

Fully agree with CountMike: do NOT connect any fan to a PSU power connector.

Now, the fact you asked this question prompts me to ask for more info. How did you plan to do that? I'm guessing some of those case fans have two connectors on their wires - a smaller one with THREE holes and wires, and a larger one with four holes not only two wires attached to that. If that is the case, all those fans with smaller THREE-hole fan connectors are 3-pin fans that require you to use Voltage Control Mode from the relevant mobo fan header. That's the only way to control the speed of 3-pin fans. If you use PWM Mode on the header, those fans will always run full speed. So, is that the type of fan you have for the (five) case fans? I am guessing that the CPU cooling fan has FOUR wires from it to a connector with FOUR holes in it.

 

[ken.manguera]

Paperdoc January 4, 2018 9:24:09 AM

Normally one would connect ONLY the CPU cooling fan to the CPU_FAN header, and all the case fans to the only SYS_FAN header you have. That is because those two headers should be set to use different temperature sensors as their reference measurement. The CPU_FAN header will us the sensor inside the CPU chip, whereas the SYS_FAN header should be configured to use a sensor on the mobo.

In your case, OP, you have five case fans. You have said you already know the current draws and have calculated the loads for use with your two Splitters, but have not said how you assigned the fans to which headers. I'm guessing you have put at least one of the case fans on the CPU_FAN header (maybe two?) which is not exactly ideal, but it certainly CAN be done that way if the fan loads are OK. I'm also guessing that connecting all five case fans to the single SYS_FAN header would violate the load limits there. So probably you have arrived at your best option already.

Fully agree with CountMike: do NOT connect any fan to a PSU power connector.

Now, the fact you asked this question prompts me to ask for more info. How did you plan to do that? I'm guessing some of those case fans have two connectors on their wires - a smaller one with THREE holes and wires, and a larger one with four holes not only two wires attached to that. If that is the case, all those fans with smaller THREE-hole fan connectors are 3-pin fans that require you to use Voltage Control Mode from the relevant mobo fan header. That's the only way to control the speed of 3-pin fans. If you use PWM Mode on the header, those fans will always run full speed. So, is that the type of fan you have for the (five) case fans? I am guessing that the CPU cooling fan has FOUR wires from it to a connector with FOUR holes in it.

For now connected all case fans directly to the psu but it's too noisy so i want to control their speed

 

[Paperdoc]

That's what I thought, So, if you use Splitters to connect the case fans plus the CPU fan to both the headers you have available, taking into account the current limit for each header, you can get than all under automatic control which will make them quieter in most situations.