Fan Controllers -- Any Fan or only Special Fans?

[WhipperSnapper]

I have a Coolermaster Aerogate 3 and it looks pretty, but I'm not sure it's working to control my fans.

I know that some fans have a third wire for RPM but I'm not sure if they just report RPM or if that's the wire that controls the speed. If you lower the voltage on a 2-wire fan, wouldn't that also slow the speed of the 2-wire fan?

Is it possible that my Aerogate 3 is just junk? ($8 or $9 at SVC...perhaps you get what you pay for.)

 

[VERTIGGO]

well, do they slow down? lowering the voltage does lower the fan speed; you can even plug in the 2 wires to the wrong side of a molex connector and use 5V for powerful fans like tornados, etc. and they will run more silently. Just be careful what you're doing, you don't want to accidentally plug in the other (12V) side into something that's meant for 5V.

 

[Zepper]

On most fans intended for PC use, the third wire (if there is one) will be yellow and reports the speed of the fan (it's a tachometer output) - it does not control the fan speed. Some fans intended for servers may have a third wire, but that wire does control the speed of the fan if your mobo supports it - that type of third wire should not be used with PCs.

Many fan controllers don't use the speed sensor wire, those that have fan speed readouts can use the third wire. All fan controllers control the power supplied to the red wire and use the black wire as ground. Linear fan controllers actually control the voltage supplied to the fan, while PWM controllers (like most CoolerMasters) control the POWER to the fan by switching the 12V on an off for various lengths of time - this switching action can cause buzzing in sleeve-bearing fans and whining in ball-bearing fans.

.bh.

 

[WhipperSnapper]

That's about what I suspected; perhaps my CoolerMaster Aerogate III is just junky. The readout displays RPM and not voltage and it seems like I can't reduce the voltage for the fans reading 0 RPM (they are blowing though). Maybe I'd be better off with a regular, knobby controller.

 

[Zepper]

Actually the CM manuals are junky - you can switch thru the fans you have hooked to the controller and set one at a time. But if the fan is only two wire, then you won't be able to know what rpm the fan is running at. You will just have to guesstimate what speed you want. And you won't get a voltage reading for the fans either as the voltage is always ~12V on PWM controllers it's just the time of the ON pulses that is varied.

.bh.

 

[WhipperSnapper]

Thanks Zepper. Actually, I figured it out about two hours ago. I can adjust the rpms for the two fans that have the third wire, but I just see zeros for the other two, however, I can adjust those as well by counting the number of "beeps" starting from lowest and then increasing the voltage.

So I take back what I might have said earlier; it seems like a fine product. Perhaps I should just consider getting two fans with a third wire to replace the two that don't have it.