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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.

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migrated from askubuntu.com Jan 12 '11 at 17:10

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Do you mean PWM (Pulse Width Modulated)? –  Moab Jan 12 '11 at 20:07
    
Yes, I want to be able to control the fan speed with PWM. –  psusi Jan 12 '11 at 20:43

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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.

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You should link your accounts, so you can take control over the question. –  AndrejaKo Jan 13 '11 at 0:35
    
PWM fans....encrypted.google.com/… –  Moab Jan 13 '11 at 1:59
    
PWM controller for 6 fans...coolermaster.com/product.php?product_id=2521 –  Moab Jan 13 '11 at 2:00
    
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 Jan 13 '11 at 18:19
    
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 Jan 17 '11 at 14:51

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