Fan Control Questions

[1Dogg2RuleAll]

Background: I am in the middle of building a system that is to be a nice compromise between power and silence. I have a question when it comes to fans and fan controllers. My motherboard will only control one fan (the cpu fan). I am trying to control 2 other fans so that occassionally I can crank it up on rpm speed, but typically will have it very low. I understand computers and most parts well, but it is the first time I have turned my attention this way towards fans and fan control...

Question: What fans can be controlled? Must they specifically state "PWM" or do they have to have a specific "connector". What is the difference between a 4 pin and 3 pin connector in regards to control if any?

Don't ask about system specs as that is irrelevant as I am asking the above question and not a question on my specific system. (I get annoyed when so many, in so many forums try to be an expert and state regurgitated info on a system,... so understand, if you can answer the question then system specs are meaningless)

 

[Fused7]

Fan controllers change the speed/noise by simply increasing the resistance and thus lowering the voltage supplied to the fan, all fans are 2 or 3 pin, with the extra third pin (yellow wire) being used for rpm monitoring

a fan may be supplied with the standard 4 pin molex, but only 2 will be wired. the point of this is so that you can daisy chain other peripherals such as extra fans/hard drives etc

 

[1Dogg2RuleAll]

That made everything clear,... I was confusing things needlessly for whatever reason (and we all get those lapses of reason). Thanks for the straightforward and clear explanation!

 

[Zepper]

Not all fan controllers adjust the voltage to the fans - just the linear ones (like the original Sunbeam Rheobus) do that. There are PWM (pulse width modulation) controllers that control the Power to the fan by delivering it in pulses of varying widths and the voltage of the pulses doesn't change (stays around 11 V). Linear controllers require fairly large heatsinks for each channel, if you don't see those, then you have a PWM controller. PWM controllers don't require PWM fans (but you can use them if you want - they will just be working like any other 3-pin fan) as the PWM chip is already in the controller, just the PWM fan controllers integrated in the motherboard require a PWM fan as the PWM chip is built into the fan instead of the controller itself. All the mobo does is generate the signal that controls the PWM chip.

.bh.