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Controlling PWM Fans

post #1 of 10
Thread Starter 
So I had 3 Coolermaster PWM fans lying around (one blademaster, others V6GT Fans) and decided to get a fan controller so I can install them in my case. I was planning to get the Lamptron FC-4, since the Sunbeam Rheobus is out of stock . Now I heard that PWM fans make more noise when controlled via a fan controller. Is that true?

Edit - I already have 3 fans on my pwm port on my mobo, and I think installing more would be too much. So a splitter isn't an option.
post #2 of 10
There won't be much control since they are PWM not voltage regulated. The chance of the fans failing quickly is very high, unless you plan to operate them at full speed 100% of the time.
post #3 of 10
There is no way PWM fans should make more noise coming from a fan controller. It's impossible.
Quote:
Originally Posted by gymenii View Post

There won't be much control since they are PWM not voltage regulated. The chance of the fans failing quickly is very high, unless you plan to operate them at full speed 100% of the time.

Please explain gymenii. I am a young electronics engineer and i don't understand how a PWM fan controller can cause PWM fans to fail more quickly. From a electronics point of view, the PWM pulses are so fast that the fan see's it as a DC voltage.

Also, i have designed PWM circuits that have the same range as voltage regulated controllers,...but i agree that most PWM controllers have a crappy range.
Edited by crimsontears809739 - 4/12/12 at 4:58pm
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post #4 of 10
He's not using a PWM fan controller.
post #5 of 10
Thread Starter 
Is there any Fan controller that you guys recommend that is under 30 dollars? I really wanted the extreme, which was only 25, but I contacted newegg and they said that they doubt they will have more in stock anytime soon. Any recommendations?
post #6 of 10
so sunbeamtech fan controllers work with PWM? interesting i would also like to know what fan controller can do this cause i dont want to mod it to a 3 pin header right now. so much work?
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post #7 of 10
Thread Starter 
http://www.newegg.com/Product/Product.aspx?Item=N82E16811995075

These support pwm, but the shipping is $6 . . .
post #8 of 10
Quote:
Originally Posted by l3eans View Post

http://www.newegg.com/Product/Product.aspx?Item=N82E16811995075

These support pwm, but the shipping is $6 . . .

This may or may not answer your questions, but thought I would post it anyway....

By design, 4 pin PWM fans are backwards compatible and will work with either a 3 pin MB fan header or voltage regulated (VR) fan controller. How well they work depends on the fan. I know from past experience that certain PWM fans do not work well or at all without a PWM control signal. The problem arises during startup. For example, using a PWM fan connected to a 3 pin MB fan header, the applied startup voltage (+VDC) off the fan header is ~12v. Most PWM fans can deal with this just fine... no problem. And after some time (usually after system startup) the voltage and fan speed is reduced based on some control signal like CPU temp. GPU fans are a good example of this... why they "rev up" during system startup.

On the other hand, using a PWM fan on a VR fan controller differ in that the individual channel controls (pots) may be set too low (or not compatible) for the fan to start up. Even when the voltage is increased, the fan will appear to start but just "pulse" back and forth. Other fans may not recognize "no PWM signal" present where 0% duty cycle = 0V, instead of +12V... and just sit there, growl and do nothing. Your comment about the noise issue when using PWM fans has some weight to it. Again, certain PWM fans deal with this ok.

Now, I know your are probably asking yourself isn't the Sunbeam Rheosmart a PWM controller?

Yes, it is but... it tricks 3 pin VR fans to operate like PWM fans, not the other way round. The only two lines on the output channels are ground and +12v. There are no PWM signals carried to any of the individual controller's output channels. If that were true, then you would see 4 pin fan connectors instead a 3 pin (actually 2 pin) and cost 2x as much!

So which controller you buy should not depend on whether its PWM, but rather... will my PWM fans work with it. Sorry again for the long post smile.gif
Edited by gymenii - 4/13/12 at 9:11pm
post #9 of 10
Thread Starter 
Quote:
Originally Posted by gymenii View Post

This may not be the answer to your questions but thought I would post it anyway....
By design, 4 pin PWM fans are backwards compatible and will work with either a 3 pin MB fan header or voltage regulated (VR) fan controller. How well they work depends on the fan. I know from past experience that certain PWM fans do not work well or at all without a PWM control signal. The problem arises during startup. For example, using a PWM fan connected to a 3 pin MB fan header, the applied startup voltage (+VDC) off the fan header is ~12v. Most PWM fans can deal with this just fine... no problem. And after some time (usually after system startup) the voltage and fan speed is reduced based on some control signal like CPU temp. GPU fans are a good example of this... why they "rev up" during system startup.
On the other hand, using a PWM fan on a VR fan controller differ in that the individual channel controls (pots) may be set too low (or not compatible) for the fan to start up. Even when the voltage is increased, the fan will appear to start but just "pulse" back and forth. Other fans may not recognize "no PWM signal" present where 0% duty cycle = 0V, instead if +12V... and just sit there, growl and do nothing. Your comment about the noise issue when using PWM fans has some weight to it. Again, certain PWM fans deal with this ok, others... well not at all.
Now, I know your are probably asking yourself isn't the Sunbeam Rheosmart a PWM controller?
Yes, it is but... it tricks 3 pin VR fans to operate like PWM fans, not the other way round. The only two lines on the output channels are ground and +12v. There are no PWM signals carried to any of the individual controller's output channels. If that were true, then you would see 4 pin fan connectors instead a 3 pin (actually 2 pin) and cost 2x as much!
So which controller you buy should not depend on whether it's PWM, but rather... will my fans work with it or not. Sorry again for the long post smile.gif

Thank you, I ordered the FC4 since it was a steal at $15. I guess I'll cross my fingers.

+1
post #10 of 10

There is a PWM controller. It's called the PWM Mate. It works. I bought one and reviewed it.

 

PWM fans usually make clicking noises. The circuitry turning on and off is what causes the noise. Noctua waited a longtime to get into PWM fans because they didn't want theirs to click. Finally they came up with switches that shift their current gradually enough to avoiding making noise doing it. I reviewed those fans here.

 

I recently studied a number of PWM fans and found the Noctua were the only ones not to click at any PWM setting. Most of the others weren't bad, though.

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