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Is there a reason to get Voltage over PWM? - Page 3

post #21 of 35
Quote:
Originally Posted by Dr Strangelove View Post

Just "having" PWM support is not a free ticket for an unrestricted control of the fan btw.
It all comes down to what the controller can finally handle. When there is a limit of min. 40% and you have a high RPM fan (which is often the case for PWM ones) but want to drive it on extra low speed you are possibly stranded.

Just had such issues on my old Hero VI which coudln't throttle my voltage regulated iPPCs (I know, shame on my for buying an industrial fan) under 800 RPM. And on my newer Z170M Mortar from MSI the min. percantage for the sys fans is even on 50%!

Its a "nice to have" owning fans that have very low minimum speed. But in the end actually the mobo is the bottle neck in a lot of threads where users complain about bad fan controls because the vendors just don't invest anything in realiable ICs or even a working software.

One more reason to go for a separate fan controller, such as an Aquaero in my case which is a really powerful gadget.

Noctua's tech department states that the iPPCs won't run under 800 rpm on voltage regardless of the controller.
post #22 of 35
True story.

But as far as I remember the onboard controller always capped at 860-880 RPM.
And 800 RPM is the factory limit of course. Maybe not the best example to express my feelings biggrin.gif
post #23 of 35
Quote:
Originally Posted by Dr Strangelove View Post

Just "having" PWM support is not a free ticket for an unrestricted control of the fan btw.
It all comes down to what the controller can finally handle. When there is a limit of min. 40% and you have a high RPM fan (which is often the case for PWM ones) but want to drive it on extra low speed you are possibly stranded.

Just had such issues on my old Hero VI which coudln't throttle my voltage regulated iPPCs (I know, shame on my for buying an industrial fan) under 800 RPM. And on my newer Z170M Mortar from MSI the min. percantage for the sys fans is even on 50%!

Its a "nice to have" owning fans that have very low minimum speed. But in the end actually the mobo is the bottle neck in a lot of threads where users complain about bad fan controls because the vendors just don't invest anything in realiable ICs or even a working software.

One more reason to go for a separate fan controller, such as an Aquaero in my case which is a really powerful gadget.
Well said! thumb.gif

I use an Aquaero 5 for most of my fan testing, both voltage and PWM. Fans will perform great! But plug them into a build using motherboard control and they often act completely different.
post #24 of 35

I am running two Noctua NF-A14 ULN's for front intake fan. Open Monitor says they are running at 750 rpm each. When I run them with LNA's they run about 600 rpm each.

 

These are fixed-speed fans. If you want variable-speed fans, go with PWM. The only question is Are the PWM circuits silent?

 

I use Gigabyte boards. The Z87 and Z97 boards have four PWM headers, a CPU, a CPU_OPT, SYS_1 and SYS_2. SYS_3 is a fixed-voltage fan header.

 

Basically, you buy a voltage-controlled fan for your case if you don't expect to vary the speeds. Buy a fan which runs the right speed and puts out the right amount of airflow and makes the right amount of noise. Then you forget about it, unless you live in a dusty place and you have to clean the filters and the fans.

 

If you expect to vary the speeds of the case fans, get PWM fans, and either put them in PWM headers or put them in a PWM splitter.

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post #25 of 35
Iirc, Asus header can control both type of fan since hasewell refresh, where asrock adapt that on skylake. The main advantage of voltage fan is probably the use of "legacy" fan like the gentle typhoon or s flex. Some pwm fan cannot stop spinning completely, where all proper voltage fan on voltage header can do(may require speed fan what not), making it semi passive. So if you run 24/7, it can slow down dust accumulation.

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post #26 of 35
As I've already posted before in some of the threads PWM isn't the end all be all. With the fans I use, on the motherboard I use them, voltage control gives me both, a wider RPM range (~250-2400 vs. ~600-2400) and quieter operation. PWM clicks at low speeds, but I believe that's a quirk of my motherboard.
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post #27 of 35
The reason a fan rated at 750rpm runs at 600rpm on LNA is because 750rpm is running open air while 600rpm is running with grill, filter, and/or whatever else is restricting airflow. tongue.gif

Brand of motherboard has little to do with what kind of control the fan headers have. It's the model of motherboard that makes the difference. Many low and mid-range boards have few PWM fan headers while new top tier boards often have many.

There is no reason to not use variable voltage control on case fans any more than there is a reason they should only be PWM controlled. Is there a reason to not use variable speed control on CPU and GPU cooler fans? We did it for many years with no problems. Last time I looked NH-D14 still comes with variable voltage fans.

There is no logic in not use temp to rpm control on case fans. The logic of varying cooler fan speed based on heat is just as applicable to case fans as it is to cooler fans. Sense all CPU fan headers and GPU fan headers that I know of vary the fan speed based on heat.
Quote:
Originally Posted by baii View Post

Iirc, Asus header can control both type of fan since hasewell refresh, where asrock adapt that on skylake. The main advantage of voltage fan is probably the use of "legacy" fan like the gentle typhoon or s flex. Some pwm fan cannot stop spinning completely, where all proper voltage fan on voltage header can do(may require speed fan what not), making it semi passive. So if you run 24/7, it can slow down dust accumulation.

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Putting it bluntly, you are making a lot of statements that are not true. mad.gif

There are "legacy" fans like Gentle Typhoon now available with PWM control.

While most PWM fans will not stop, it is not because they are PWM, but because their PWM control (internal) and or external) is not programmed to stop them. I think newer GPUs that turn off their fans below a certain temp are using PWM fans.

Few variable control motherboard headers and no fans I know of are designed to stop running at low voltage.

Variable voltage fans need the power off when they stop. It's not a good idea to just lower the voltage until they stop. While we can often get away with stalling fans at too low a voltage, it can cause damage.
Quote:
Originally Posted by Loladinas View Post

As I've already posted before in some of the threads PWM isn't the end all be all. With the fans I use, on the motherboard I use them, voltage control gives me both, a wider RPM range (~250-2400 vs. ~600-2400) and quieter operation. PWM clicks at low speeds, but I believe that's a quirk of my motherboard.
Exactly! thumb.gif
It is not a PWM versus variable voltage.
It is all what combination of components works best.
What controller is used (motherboard or independent).
Some are much better at PWM, some are much better at variable voltage, and some are not good at either.
post #28 of 35
Quote:
Originally Posted by doyll View Post

The reason a fan rated at 750rpm runs at 600rpm on LNA is because 750rpm is running open air while 600rpm is running with grill, filter, and/or whatever else is restricting airflow. tongue.gif

. . .

Actually, the fans run 750rpm behind filters. One is  running in front of the hard drives; the other to open air. Their rpms are within 2% of each other. When I put LNA's on them, they ran about 600 rpm under the identical conditions -- I did not move the fans, just inserted LNA's to see how fast they ran. In the event, the LNA's were not enough quieter to make up for the loss of airflow. When it is the on ly machine running in the room, I can barely hear it even though it sits 20 inches (0.5m) from my ear. when another machine is operating, that one is much louder, even though it is across the room --  about 10 feet away. Combine Noctua ULN's with an R5 and the result is near silence.

 

I am glad that some can run voltage-controlled fans through a wide range of speeds. But voltage control can introduce noise if it is done wrong. This is why I have given up of variable voltage control when testing fans.

 

PWM noise is usually a function of older circuit design in fans. That a mb makes PWM noise is unfortunate.

 

I continue in my own practice of leaving voltage fans alone. When I want variable speeds I use PWM. In fact, you can get PWM Gentle Typhoon fans. I have a 2150rpm fan from the Tao Bao group buy that is probably the apotheosis of heatsink fans. But if you want to vary the speeds of your voltage fan, fell free to do so. Getting a high quality voltage controller for your rig seems a waste of money from where I sit. But YMMV.

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post #29 of 35
Quote:
Originally Posted by ehume View Post

Actually, the fans run 750rpm behind filters. One is  running in front of the hard drives; the other to open air. Their rpms are within 2% of each other. When I put LNA's on them, they ran about 600 rpm under the identical conditions -- I did not move the fans, just inserted LNA's to see how fast they ran. In the event, the LNA's were not enough quieter to make up for the loss of airflow. When it is the on ly machine running in the room, I can barely hear it even though it sits 20 inches (0.5m) from my ear. when another machine is operating, that one is much louder, even though it is across the room --  about 10 feet away. Combine Noctua ULN's with an R5 and the result is near silence.

I am glad that some can run voltage-controlled fans through a wide range of speeds. But voltage control can introduce noise if it is done wrong. This is why I have given up of variable voltage control when testing fans.

PWM noise is usually a function of older circuit design in fans. That a mb makes PWM noise is unfortunate.

I continue in my own practice of leaving voltage fans alone. When I want variable speeds I use PWM. In fact, you can get PWM Gentle Typhoon fans. I have a 2150rpm fan from the Tao Bao group buy that is probably the apotheosis of heatsink fans. But if you want to vary the speeds of your voltage fan, fell free to do so. Getting a high quality voltage controller for your rig seems a waste of money from where I sit. But YMMV.
Sounds like your fans are very good. and your ressitance is minimal. That or the free air one may run a little slower in if switched with filter one. Either way it's not worth talking about.

What I was getting at is that more resistance causes more load on the fan, and this cases them to spin slower at same power setting. How much slower depends on how much power they have. You know this. It's like a 300hp car and a 50hp car going up the same hill. The 300hp car can do it at higher mph and lower rpm using less throttle than the 50 hp car can.

I agree with you about PWM vs variable voltage in as much as all my system s that are not in Phanteks cases with their PWM controlled fan hub controlling their variable voltage fans are using all PWM fans.

Continue in your practices by all means. thumb.gif
Just don't say voltage control is not an acceptable way of controlling fan speed. I know you know that LNA and ULNA are nothing but voltage control modules, so if you believe voltage fans should not be used with variable voltgage control you better get rid of all of them because either you are being illogical about voltage control or are not as smart as I know you are. tongue.gif
post #30 of 35
Quote:
Originally Posted by doyll View Post

Putting it bluntly, you are making a lot of statements that are not true. mad.gif

There are "legacy" fans like Gentle Typhoon now available with PWM control.

While most PWM fans will not stop, it is not because they are PWM, but because their PWM control (internal) and or external) is not programmed to stop them. I think newer GPUs that turn off their fans below a certain temp are using PWM fans.

Few variable control motherboard headers and no fans I know of are designed to stop running at low voltage.

Variable voltage fans need the power off when they stop. It's not a good idea to just lower the voltage until they stop. While we can often get away with stalling fans at too low a voltage, it can cause damage.

I never said anything how or why they wont stop, I just stating a simple fact "some pwm fan cannot be stopped on pwm header", whether it is by deign or technical limitation have nothing to do with the discussion.

it can cause damage, ok. redface.gif
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