Overclock.net › Forums › Cooling › Air Cooling › Choosing fans for the case front panel...
New Posts  All Forums:Forum Nav:

Choosing fans for the case front panel... - Page 3

post #21 of 26
Quote:
Originally Posted by EMUracing View Post

My understanding is that it is not recommended to use pwm control at the same time as lowering voltage. The pwm circuitry is essentially bypassed when no pwm signal is present.

So, using a voltage reducing adapter in conjunction with pwm control is not recommended.
Correct, if no PWM signal is present the fan functions as a normal 12 volt fan. But that does not mean PWM fans cannot be used with variable voltage control


Noctua website in NF-A15 PWM, NF-A14 PWM, fan says
Quote:
Low-Noise Adaptor
The NF-A15 PWM is supplied with a (L.N.A.) that reduces the maximum fan speed from 1200 to 900rpm. The L.N.A. can be used either to run the fan at a fixed speed of 900rpm or to cap the maximum speed when using automatic PWM control.
It says same for F-A20, NF-A12x15, NF-A12 .. and I stopped looking.

My understanding of the English language interprets that to mean Noctua is saying it is fine to use LNA with PWM control. Which contradicts what you said.

So please supply some links to credible sources supporting your claims or stop making them.
post #22 of 26
Quote:
Originally Posted by doyll View Post

So please supply some links to credible sources supporting your claims or stop making them.
It's not just coming out of nowhere, it comes from a statement by Nidec a few years ago:

Pulse-width modulation of DC operating voltage to modify fan speed is not recommended. Transients generated by that approach can irreversibly damage motor commutation and control electronics and dramatically shorten the life of a fan.

Of course, that's basically saying: running a DC fan with PWM is bad... but it probably got misinterpreted over time. And for some fans, voltage control + PWM might actually not mix well.

Given that Noctua includes voltage adaptors with their PWM fans (meaning they're covered by their long warranty), however, it's clearly not an issue for Noctua's PWM implementation within the range provided by the Noctua adaptors - they probably designed their PWM circuitry to handle that.

EDIT: Slightly misread the statement before, corrected my comment to make more sense.
Edited by ErrantPigeon - 9/19/17 at 2:54pm
Iridium
(14 items)
 
  
CPUMotherboardGraphicsRAM
i7-3770k Asus P8Z77-V EVGA GTX 1070 FTW 4x 4 GB Corsair Vengeance LP DDR3 
Hard DriveHard DriveHard DriveCooling
Samsung 850 EVO Seagate Barracuda 1TB 7200rpm WD Blue 3TB 5400rpm Noctua NH-D15S 
OSMonitorKeyboardCase
Microsoft Windows 10 Pro Acer XR341CK CODE TKL ISO Keyboard (Cherry MX Clear) Phanteks Evolv ATX 
Mouse
Logitech G603 
  hide details  
Reply
Iridium
(14 items)
 
  
CPUMotherboardGraphicsRAM
i7-3770k Asus P8Z77-V EVGA GTX 1070 FTW 4x 4 GB Corsair Vengeance LP DDR3 
Hard DriveHard DriveHard DriveCooling
Samsung 850 EVO Seagate Barracuda 1TB 7200rpm WD Blue 3TB 5400rpm Noctua NH-D15S 
OSMonitorKeyboardCase
Microsoft Windows 10 Pro Acer XR341CK CODE TKL ISO Keyboard (Cherry MX Clear) Phanteks Evolv ATX 
Mouse
Logitech G603 
  hide details  
Reply
post #23 of 26
Quote:
Originally Posted by ErrantPigeon View Post

It's not just coming out of nowhere, it comes from a statement by Nidec a few years ago:

Pulse-width modulation of DC operating voltage to modify fan speed is not recommended. Transients generated by that approach can irreversibly damage motor commutation and control electronics and dramatically shorten the life of a fan.

Of course, that's basically saying: running a DC fan with PWM is bad... but it probably got misinterpreted over time. And for some fans, voltage control + PWM might actually not mix well.

Given that Noctua includes voltage adaptors with their PWM fans (meaning they're covered by their long warranty), however, it's clearly not an issue for Noctua's PWM implementation within the range provided by the Noctua adaptors - they probably designed their PWM circuitry to handle that.

That's not even remotely related, read their statement again, but slowly.

They're talking about using an external PWM controller to pulse power to a DC fan. That's not how PWM fans work, at all. And neither does it have anything to do with variable voltage on PWM fans,

PWM fans take a PWM signal (not power pulses!) from a the motherboard or fan controller and then the PCB on the fan uses that to regulate its speed with proper pulses. This is not the same as brute forcing PWM onto a DC fan.

Edit: I see that you edited your post, dunno if i misread something first or if what i said is no longer relevant because of the edit, oh well.
Edited by Gilles3000 - 9/19/17 at 3:07pm
post #24 of 26
Quote:
Originally Posted by ErrantPigeon View Post

It's not just coming out of nowhere, it comes from a statement by Nidec a few years ago:

Pulse-width modulation of DC operating voltage to modify fan speed is not recommended. Transients generated by that approach can irreversibly damage motor commutation and control electronics and dramatically shorten the life of a fan.

Of course, that's basically saying: running a DC fan with PWM is bad... but it probably got misinterpreted over time. And for some fans, voltage control + PWM might actually not mix well.

Given that Noctua includes voltage adaptors with their PWM fans (meaning they're covered by their long warranty), however, it's clearly not an issue for Noctua's PWM implementation within the range provided by the Noctua adaptors - they probably designed their PWM circuitry to handle that.

EDIT: Slightly misread the statement before, corrected my comment to make more sense.

What @Gilles3000 said. thumb.gif

Original ErrantPigeon post
Quote:
It's not just coming out of nowhere, it comes from a statement by Nidec a few years ago. Given Nidec's excellent design of the Gentle Typhoon, I'd believe them... for their PWM implementation.

Given that Noctua includes voltage adaptors with their PWM fans (meaning they're covered by their long warranty), however, it's clearly not an issue for Noctua's PWM implementation within the range provided by the Noctua adaptors - they probably designed their PWM circuitry to handle that.
Your Nidec quote is about using PWM control on variable voltage fans, not about using variable voltage on PWM fans.

While Noctua PWM many have slightly smoother pulses, it is not significantly different than other good quality fans .. and probably many lower quality fans too. Much of their talk is just good old fashion advertising hype. There are many complaints about Noctua fans clicking at low PWM speeds. tongue.gif

And off you go again making suppositions without any facts or proof to support them.

I've included your edited post too:
Quote:
Originally Posted by Gilles3000 View Post

That's not even remotely related, read their statement again, but slowly.

They're talking about using an external PWM controller to pulse power to a DC fan. That's not how PWM fans work, at all. And neither does it have anything to do with variable voltage on PWM fans,

PWM fans take a PWM signal (not power pulses!) from a the motherboard or fan controller and then the PCB on the fan uses that to regulate its speed with proper pulses. This is not the same as brute forcing PWM onto a DC fan.

Edit: I see that you edited your post, dunno if i misread something first or if what i said is no longer relevant because of the edit, oh well.
post #25 of 26
Quote:
Originally Posted by doyll View Post

Correct, if no PWM signal is present the fan functions as a normal 12 volt fan. But that does not mean PWM fans cannot be used with variable voltage control


Noctua website in NF-A15 PWM, NF-A14 PWM, fan says

It says same for F-A20, NF-A12x15, NF-A12 .. and I stopped looking.

My understanding of the English language interprets that to mean Noctua is saying it is fine to use LNA with PWM control. Which contradicts what you said.

So please supply some links to credible sources supporting your claims or stop making them.
In my experience trying a voltage reducing adapter with cougar fans, it effected the whole range of rpm and produced a very small window of operation and the pulses were audible when between 40 and 100% operation.

Noctua may specifically design their fans for use at lower voltages, but other fans may have ill effects when lowering voltage and using pwm.

I would recommend either using pwm or voltage control, not both. In software you can set the maximum pwm rate, and the curve will be unaffected. There might be some special cases that need to use a voltage adapter, such as higher speed fans on an aio that does not have adjustable software, but those are outliers for the most part.

I never said that it would be damaging to the fan, but just that it is not recommended. If you need to use a voltage adapter on a pwm fan, you bought the wrong fan.
Quote:
Designated PWM fans not only have internal circuitry which differs from that of standard fans, but because they are designed with speed control in mind the motors themselves are usually more advanced (and expensive). So, PWM speed control of a standard fan is indeed very different from PWM speed control of a PWM fan… Nidec even goes so far as to say that modulating the main supply voltage is not advisable
Quoted from the article listed above. The quote gilles posted is referring to supply voltage to pwm fans, and that it should not be modulated (by pwm voltage control, but true voltage control should not cause damage, just lower the speeds across the range since you replace 12v with 7v or 9v).
Edited by EMUracing - 9/20/17 at 1:38am
post #26 of 26
Quote:
Originally Posted by EMUracing View Post

In my experience trying a voltage reducing adapter with cougar fans, it effected the whole range of rpm and produced a very small window of operation and the pulses were audible when between 40 and 100% operation.

Noctua may specifically design their fans for use at lower voltages, but other fans may have ill effects when lowering voltage and using pwm.

I would recommend either using pwm or voltage control, not both. In software you can set the maximum pwm rate, and the curve will be unaffected. There might be some special cases that need to use a voltage adapter, such as higher speed fans on an aio that does not have adjustable software, but those are outliers for the most part.

I never said that it would be damaging to the fan, but just that it is not recommended. If you need to use a voltage adapter on a pwm fan, you bought the wrong fan.
Quoted from the article listed above. The quote gilles posted is referring to supply voltage to pwm fans, and that it should not be modulated (by pwm voltage control, but true voltage control should not cause damage, just lower the speeds across the range since you replace 12v with 7v or 9v).
I have not tried LNA's on cougar fans but have on Phanteks and Thermalright with no noticeable differences other than lower idle and maximum speeds. No idea why pulse would be audible. The P'WM circuitry is on separate circuit with different voltage (5.5v if memory serves)

As you know the original discussion was Missaka wanting fan info and Arctic F12 PWM and him being told he needed to be sure his motherboard fan header was PWM for PWM fans. That is when I said PWM fans work just fine on variable voltage and nanotm posted about that shortening fan life to use variable voltage on PWM fans. When you posted following that I was trying to make it clear that using variable voltage does not damage or wear out PWM fans and I assumed your post was related to that as well. Sorry I misunderstood.

As for using voltage reduction and PWM I have seen nothing from the fan companies I am familiar with saying it is not recommended, but I am not conversant on all the other fan companies out there. Could you post some links to companies saying not to use voltage reduction with PWM fans?
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Air Cooling
Overclock.net › Forums › Cooling › Air Cooling › Choosing fans for the case front panel...