Doubts about connecting fans to the motherboard
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Hello,
I have an Asus Maximus VIII Hero motherboard to which I will be fitting a Corsair H100i v2 liquid cooler and I have calculated that I will need 8 or 9 fans (I will be using a wooden case to build the computer).
The thing is, I see that the motherboard has all these types of connections for ventilation:CPU_OPT (4pines)
CPU_FAN (4p)
W_PUMP (4p)
CHA_FAN1,CHA_FAN2,CHA_FAN3,CHA_FAN4 (4p)
EXT_FAN (5p)From what I have read, the fourth pin is for controlling the fan speed. I want them to be able to be controlled automatically but also manually. Is this possible at the same time?
I imagine that CPU_OPT, CPU_FAN and W_PUMP are for connecting the two fans of the H100i v2 and the water pump but I am not sure. Is that right?
Another question I have: When controlling the fan speed, is there a distinction between the CPU_OPT, CPU_FAN and CHA_FAN connectors or are they all controlled in the same way (either by the motherboard or by software)?
What is the difference between the EXT_FAN and the CHA_FAN?
For monitoring/controlling the ventilation (among other things) I was thinking of the "Asus ROG Frontal Base" although I am open to other possibilities.
Thank you very much
Best regards. -
Manual and automatic depend on the software, then you have the 4-pin PWM regulation where one pin is 12V and the other is pulses, 12V shocks. There is also voltage regulation where with 3 pins, what in PWM are 12V, in these it varies delivering 12V or less. Looking at the manual for the board you should be able to discern what regulates each connector and see if you need 3 or 4-pin fans.
If you want to get into the details, some concepts need to be clarified. Be careful when connecting more than 3 fans to a connector, if they ask for too much at startup you could end up burning the board connectors.
I would recommend SpeedFan for automatic or manual regulation, but really, if you fine-tune an automatic one you forget about it, there's no need to touch it except in very exceptional situations like stress tests to beat records or some test you feel like doing. The software is a bit tedious but it's one of the best, once you adjust it you can relax.
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Hello Obione, I do not understand this about " Be careful when connecting more than 3 fans to one connector". I thought that a single connector could only connect a single fan…..
Best regards. -
I, for that mess of fans, would rather get a four-channel rehobus and connect a couple per channel and to the power supply.
And I say mess because if you have to reach that number of fans to cool the equipment, something hasn't been done right.
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Hello Whoololon,
In this thread I put the idea of what I want to build, but I'm not really sure if the number of fans is adequate.The truth is that I would really appreciate some recommendations in this regard as well as their location.
Thanks for the comment

Regards -
Except for fans with many RPMs, you can connect a pair with an adapter. In fact, I have 3 in one connector, but my fans require little at startup, which is the strongest peak.
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If I remember correctly, but back then there were four more on the radiator. ¬¬
The motherboard is for what it is, I mean that if you take it out of what it should do, which is to feed a processor, RAM, etc., and you start adding extra load, we run the risk of it dying sooner rather than later.
Attaching fans to its connectors is something unnecessary, as Obione points out, you can stretch the amperage of each one with two fans, but it's better to have one per connector.
And it's unnecessary because we have two options:
- Connecting them to a rehobus/electrobus to adjust the RPMs, and taking the energy from a solitary branch of our power supply.
- Connecting a fan header card. In fact, there are Asus models that come with one.
Then there's the issue of noise; because we can already spend the money on "ultrasupermegasilenciosos" models :ugly:, which with that amount of noise they can be heard.
In summary, connecting to the motherboard directly is possible, but not in such quantity.
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Good morning,
Thank you Obione and Woololon for your contributions, now I see it MUCH clearer.
Let's see if I can bring this to a successful conclusion
Best regards