How to add more 4 pin fan controllers (hardware hacking)

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I'm looking at building a new system and most of the good cases come with several fans, but most of the motherboards I've looked at only have one 4 pin case fan header. I'm looking for a guide on hacking in an additional hwmon compatible controller to add a few more 4 pin PWM fan headers so I can have the fancontrol package slow and spin down all the fans when the system is cool and idle.

psusi

Posted 2011-01-12T15:21:06.473

Reputation: 7 195

Do you mean PWM (Pulse Width Modulated)? – Moab – 2011-01-12T20:07:17.597

Yes, I want to be able to control the fan speed with PWM. – psusi – 2011-01-12T20:43:28.053

Answers

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After reading everything I could find on the subject, it seems that the 4th pin contains the raw PWM signal, and the fan is expected to contain the mosfet and bypass diode required to use the PWM signal to regulate the voltage down from the 12v supply. It seems that I can add another hwmon controller described here:

http://www.lm-sensors.org/wiki/HardwareHacking

The motherboard I am thinking of buying has one 4 pin and two 3 pin fan headers, and the case has 3 fans, so what I think I will do is break the PWM pin out of the 4 pin and split it out to all 3 fans. The motherboard might not be able to sink the combined current, so I will probably add a transistor to boost the signal.

That should let me control the speed of multiple fans, just not independently of each other. Now I'm just having a hard time finding 4 pin fans.

psusi

Posted 2011-01-12T15:21:06.473

Reputation: 7 195

You should link your accounts, so you can take control over the question. – AndrejaKo – 2011-01-13T00:35:55.293

PWM controller for 6 fans...http://www.coolermaster.com/product.php?product_id=2521

– Moab – 2011-01-13T02:00:10.710

I've been looking into getting one of those 5.25 inch bay fan controllers. I will probably end up going that route, though I'd rather have software control and monitoring. – psusi – 2011-01-13T18:19:47.443

I was looking at a nice coolermaster fan controller but after emailing them, it turns out that it completely ignores the PWN signal from the motherboard and the fans are under complete manual control. No good. Guess I'm going to have to go with the homebrew. – psusi – 2011-01-17T14:51:59.490