Overclock.net banner

Using different fans with PWM splitter

9K views 26 replies 4 participants last post by  doyll 
#1 ·
Hi guys,

So my plan was to use the Corsair ML series: 3 120mm and 140mm fans each. I'll also be using the Swiftech 8 way PWM fan splitter. My concern is that, as shown in the picture below, it takes the RPM signal from one of the devices which could lead to complications when aligning the RPMs between the 120 and 140 mm fans. The 120s and 140s run at an RPM of 2400 & 2000 respectively. Is this a valid concern?

Another issue is that I've been reading threads where Corsair fans have an issue where they require a stronger RPM signal than most others. Is this still the case with the ML series?

 
See less See more
1
#2 ·
Quote:
Originally Posted by rayven1lk View Post

Hi guys,

So my plan was to use the Corsair ML series: 3 120mm and 140mm fans each. I'll also be using the Swiftech 8 way PWM fan splitter. My concern is that, as shown in the picture below, it takes the RPM signal from one of the devices which could lead to complications when aligning the RPMs between the 120 and 140 mm fans. The 120s and 140s run at an RPM of 2400 & 2000 respectively. Is this a valid concern?

Another issue is that I've been reading threads where Corsair fans have an issue where they require a stronger RPM signal than most others. Is this still the case with the ML series?

I personally had problems with ML120 fans running properly combined with other brand 120mm fans (constant max RPM), while 3-4 ML120 fans in 1 pwm fan splitter work just fine.
 
#3 ·
Quote:
Originally Posted by Arengeta View Post

I personally had problems with ML120 fans running properly combined with other brand 120mm fans (constant max RPM), while 3-4 ML120 fans in 1 pwm fan splitter work just fine.
Interesting. What kinda problems did you run into?
And to clarify, when you removed the other brand 120mm fans from the splitter is when the ML120s did their job?
 
#4 ·
Quote:
Originally Posted by rayven1lk View Post

Interesting. What kinda problems did you run into?
And to clarify, when you removed the other brand 120mm fans from the splitter is when the ML120s did their job?
As I stated in my previous post the ML120 were running at high rpm all the time, but that could have been due to 600-1500 RPM range on the other fan, so 900 RPM were equal to 1500-1600RPM on ML120. Maybe it wouldn't be a problem if other fans have the same RPM range as ML120's.
But yes, after removing the other fan the ML120's started working as intended.
 
#5 ·
Quote:
Originally Posted by Arengeta View Post

As I stated in my previous post the ML120 were running at high rpm all the time, but that could have been due to 600-1500 RPM range on the other fan, so 900 RPM were equal to 1500-1600RPM on ML120. Maybe it wouldn't be a problem if other fans have the same RPM range as ML120's.
But yes, after removing the other fan the ML120's started working as intended.
Fan rpm is not a fixed ration or percentage of PWM signal. The PWM signal to rpm is part of the programming in PWM circuitry in fan.
Here are some examples. Black graph line (top line in chart) is fan rpm; PWM % is shown across bottom of chart. Notice how all of these fans are flat-lining at idle at different minimum PWM% signal. Also notice how their respective PWM% to rpm is not a the same progression for each fan .. it is not a linear progression, but is instead a custom progression that is programmed into each fan's internal PWM circuit.
wink.gif



All graphs are from Thermalbench.com fan tests and reviews.
 
  • Rep+
Reactions: gupsterg
#6 ·
Quote:
Originally Posted by doyll View Post

Fan rpm is not a fixed ration or percentage of PWM signal. The PWM signal to rpm is part of the programming in PWM circuitry in fan.
Here are some examples. Black graph line (top line in chart) is fan rpm; PWM % is shown across bottom of chart. Notice how all of these fans are flat-lining at idle at different minimum PWM% signal. Also notice how their respective PWM% to rpm is not a the same progression for each fan .. it is not a linear progression, but is instead a custom progression that is programmed into each fan's internal PWM circuit.
wink.gif



All graphs are from Thermalbench.com fan tests and reviews.
Thanks for justifying. Well, it seems that ML120 have their own PWM circuit so it might be hard for you to control them effectively with other fans.
 
#7 ·
Quote:
Originally Posted by Arengeta View Post

Thanks for justifying. Well, it seems that ML120 have their own PWM circuit so it might be hard for you to control them effectively with other fans.
All PWM fans have their own PWM circuit and all PWM circuits have their own %PWM to rpm curves.
Here is RM 120 PWM% to rpm curve
 
  • Rep+
Reactions: rayven1lk
#9 ·
Quote:
Originally Posted by rayven1lk View Post

Thanks guys. So looks like the takeaway is to stick to using the same fans on a controller. And not to mix them with other fans since the RPM to PWM curve profile is unique to each series.
I don't think that is necessarily true.

Maybe we need find out what the PWM% / rpm curve is of fans you are interested in using on a PWM hub / PWM splitter so the fans you choose have complementary PWM% / rpm profiles for your needs rather than all being the same . For example like they all idle and advance at similar PWM% / rpm or maybe some doing one curve while others do another .. like if using 4x intakes and 2x exhaust fans it might be advisable to have exhaust fans that increase rpm at a faster rate than the 4x intake fans do .. so the exhaust can help by moving as much air out as the intakes are bringing in out at higher PWM% rates.

If we don't have enough individual PWM control sources to do what we want, we have to use some other way to get what we want
wink.gif
 
#10 ·
Quote:
Originally Posted by doyll View Post

I don't think that is necessarily true.

Maybe we need find out what the PWM% / rpm curve is of fans you are interested in using on a PWM hub / PWM splitter so the fans you choose have complementary PWM% / rpm profiles for your needs rather than all being the same . For example if using 4x intakes and 2x exhaust fans it might be advisable to have exhaust fans that increase rpm at a faster rate than the 4x intake fans do .. so the exhaust can help by moving as much air out as the intakes are bringing in out at higher PWM% rates.

If we don't have enough individual PWM control sources to do what we want, we have to use some other way to get what we want
wink.gif
I'm still trying to figure it out. I'll be using 2 rads (front and top). Front rad will be 360 intake, top rad 280 exhaust and one exhaust case fan (140mm). I definitely would like to go with the ML series, but still not sure about how the 2 different sizes would compliment eachother.
 
#11 ·
If you're planning on using 2 sizes of fans from the same series & manufacturer, I would say they're more likely to work out well. Of course, without the RPM/PWM charts for both, I'm just guessing, but it doesn't seem unreasonable. The max RPM vs diameter of the 2 fans you're considering are nicely matched. I couldn't justify spending what the ML series fans cost, but if they're what you want, I say go for it, & let us know how it works out.
 
#12 ·
Quote:
Originally Posted by dlewbell View Post

If you're planning on using 2 sizes of fans from the same series & manufacturer, I would say they're more likely to work out well. Of course, without the RPM/PWM charts for both, I'm just guessing, but it doesn't seem unreasonable. The max RPM vs diameter of the 2 fans you're considering are nicely matched. I couldn't justify spending what the ML series fans cost, but if they're what you want, I say go for it, & let us know how it works out.
I'm open to recommendations. But they don't seem to be priced that much higher than Vardars, Noctuas, etc...
 
#13 ·
Quote:
Originally Posted by rayven1lk View Post

I'm still trying to figure it out. I'll be using 2 rads (front and top). Front rad will be 360 intake, top rad 280 exhaust and one exhaust case fan (140mm). I definitely would like to go with the ML series, but still not sure about how the 2 different sizes would compliment eachother.
I doubt I would use ML series, but a few suggestions are that 2x 140mm fans will move similar amounts of air as 3x 120mm fans do. Looking at Thermalbench rests of ML fans through a Swiftech MCR140QP & MCR120QP radiators at 100% PWM
ML120 is about 400fpm
ML140 is about 540fpm
Corsair claims
ML120 is 75cfm; 3x = 225cfm; if filters reduce flow by 15% = 192cfm ..
ML140 is 97cfm; 3x = 194cfm
Very near equal airflow in and out.
wink.gif


Not this ia all theory and calculation. We need to build it and see if it is indeed balance or not. Testing with incense sticks smoke, cigarette smoke, candle flame, etc. to see if other vents and holes are leaking air in or out. We may very well need another fan, like a filtered bottom intake to make sure air is leaking out.

But I doubt we will want more exhaust fans.
wink.gif

If you used any more exhaust fans they will be exhausting more air then the intake fans are bring in .. meaning air will be leaking in unused vents and holes bringing dust in at the same time.
 
#14 ·
Quote:
Originally Posted by doyll View Post

I doubt I would use ML series, but a few suggestions are that 2x 140mm fans will move similar amounts of air as 3x 120mm fans do. Looking at Thermalbench rests of ML fans through a Swiftech MCR140QP & MCR120QP radiators at 100% PWM
ML120 is about 400fpm
ML140 is about 540fpm
Corsair claims
ML120 is 75cfm; 3x = 225cfm; if filters reduce flow by 15% = 192cfm ..
ML140 is 97cfm; 3x = 194cfm
Very near equal airflow in and out.
wink.gif


Not this ia all theory and calculation. We need to build it and see if it is indeed balance or not. Testing with incense sticks smoke, cigarette smoke, candle flame, etc. to see if other vents and holes are leaking air in or out. We may very well need another fan, like a filtered bottom intake to make sure air is leaking out.

But I doubt we will want more exhaust fans.
wink.gif

If you used any more exhaust fans they will be exhausting more air then the intake fans are bring in .. meaning air will be leaking in unused vents and holes bringing dust in at the same time.
Thanks for the example. I don't think I'll be able to have a filtered bottom intake since the case is a phantex enthoo evolv atx.
Also why do you say you doubt you'll use ML series?
 
#15 ·
Quote:
Originally Posted by rayven1lk View Post

Thanks for the example. I don't think I'll be able to have a filtered bottom intake since the case is a phantex enthoo evolv atx.
Also why do you say you doubt you'll use ML series?
Well, for one thing they are a new release with not many months of use to prove their reliability. The ML120 is doing quite well so far, but there seem to be some problems with vibration and noise with ML140. At least I have seen some posts to that effect. But mostly I don't like the company as well as I do others.
tongue.gif
 
#16 ·
Quote:
Originally Posted by doyll View Post

Well, for one thing they are a new release with not many months of use to prove their reliability. The ML120 is doing quite well so far, but there seem to be some problems with vibration and noise with ML140. At least I have seen some posts to that effect. But mostly I don't like the company as well as I do others.
tongue.gif
Lol, would you be kind enough to make some suggestions? This is my first build so I'm fairly new to all of this
smile.gif

And how did Corsair do wrong by you and others?
tongue.gif
 
#17 ·
Quote:
Originally Posted by rayven1lk View Post

Lol, would you be kind enough to make some suggestions? This is my first build so I'm fairly new to all of this
smile.gif

And how did Corsair do wrong by you and others?
tongue.gif
I'm not going into details of why I don't use them. Suffice to say many computer people have the same opinion I do.
tongue.gif


As for what fans to get, I suggest you look at some compent tests & reviews. Thermalbench.com does a good test and review of product. while all his graphs are good, the most important one is the airflow to noise graph. He is using radiators as a basis for resistance and also as an airflow straightener, then measuring airflow speed, not volume. Like I said above, 3x 120mm fans will move about the same amount of air as 2x 140mm fans of similar design. I've often seen 2x 140mm fans move a little more than 3x 120mm fans, but it depends on applicaiton. Phanteks, Noctua, Thermalright, new be quiet!, Silverstone etc. are good fans I have used, but they are by no means the only good fans.

If we want to get techical and calculate their volume (CFM), we have to take the area of the fan (diameter minus the area of the motor hub) and multiply that by the airflow's speed (FPM). A good average of airflow area for most 120mm fans is about 100sq cm and for 140mm fans is about 144sq cm.

Once you have some ideas of what fans are to your liking I will help with any questions about them.
 
#18 ·
Quote:
Originally Posted by doyll View Post

I'm not going into details of why I don't use them. Suffice to say many computer people have the same opinion I do.
tongue.gif


As for what fans to get, I suggest you look at some compent tests & reviews. Thermalbench.com does a good test and review of product. while all his graphs are good, the most important one is the airflow to noise graph. He is using radiators as a basis for resistance and also as an airflow straightener, then measuring airflow speed, not volume. Like I said above, 3x 120mm fans will move about the same amount of air as 2x 140mm fans of similar design. I've often seen 2x 140mm fans move a little more than 3x 120mm fans, but it depends on applicaiton. Phanteks, Noctua, Thermalright, new be quiet!, Silverstone etc. are good fans I have used, but they are by no means the only good fans.

If we want to get techical and calculate their volume (CFM), we have to take the area of the fan (diameter minus the area of the motor hub) and multiply that by the airflow's speed (FPM). A good average of airflow area for most 120mm fans is about 100sq cm and for 140mm fans is about 144sq cm.

Once you have some ideas of what fans are to your liking I will help with any questions about them.
doyll, sorry to jump in another thread. But can you explain the difference between be quiet! silent wings 2 pwm, be quiet! shadow wings 1 pwm and be quiet! silent wings 3 pwm? All fans are 120mm.
Which is worth getting considering they are around the same price point?
 
#21 ·
Quote:
Originally Posted by Arengeta View Post

Wait, what? It's you who's trolling me!
cheers.gif
p2WAI84.png
There is no '1' on 'Silent Wings' fans , there is no 'Silent Wings 1'.
The only 'Silent Wihgs 2 PWM' fans listed are 80mm and 92mm. There are no 'Silent Wings 2' 120mm fans .. and you want my input on 3 different model of 120mm fans. So how is my reply even remotely trolling you?
poke.gif
biggrin.gif
 
#22 ·
Quote:
Originally Posted by doyll View Post

There is no '1' on 'Silent Wings' fans , there is no 'Silent Wings 1'.
The only 'Silent Wihgs 2 PWM' fans listed are 80mm and 92mm. There are no 'Silent Wings 2' 120mm fans .. and you want my input on 3 different model of 120mm fans. So how is my reply even remotely trolling you?
poke.gif
biggrin.gif
Shadow Wings 1, not Silent Wings 1
tongue.gif
poke.gif

But yeah, Silent Wings 2 are no more listed on be quiet! website. However they had the same stats as shadow wings but had 16.5dBa noise level compared to 18.9 on Shadow Wings.
Then lets round it to Shadow Wings and Silent Wings 3.
 
#23 ·
Quote:
Originally Posted by Arengeta View Post

Shadow Wings 1, not Silent Wings 1
tongue.gif
poke.gif

But yeah, Silent Wings 2 are no more listed on be quiet! website. However they had the same stats as shadow wings but had 16.5dBa noise level compared to 18.9 on Shadow Wings.
Then lets round it to Shadow Wings and Silent Wings 3.
Shadow Wings/Silent Wings/No Wings.....
Silent Wings 2 are listed, just no 120mm fans in it's list.
tongue.gif

To be honest I have only used be quiet! fans supplied on their coolers. They are supply plenty of airflow at nice low noise levels .. at or below what I can hear in a 30db room. Beyond that, higher static pressure ratings mean more ability to overcome resistance, and anything (grill, filter, fins, etc) is resistance andlowers the airflow below airflow rating and so does lower the rpm from maximum.
 
#24 ·
Quote:
Originally Posted by doyll View Post

Shadow Wings/Silent Wings/No Wings.....
Silent Wings 2 are listed, just no 120mm fans in it's list.
tongue.gif

To be honest I have only used be quiet! fans supplied on their coolers. They are supply plenty of airflow at nice low noise levels .. at or below what I can hear in a 30db room. Beyond that, higher static pressure ratings mean more ability to overcome resistance, and anything (grill, filter, fins, etc) is resistance andlowers the airflow below airflow rating and so does lower the rpm from maximum.
In short:
Shadow Wings aka Silent Wings 2 - 1500RPM 50.5CFM with air pressure 1.62mm H2O
Silent Wings 3 - 1450 RPM 50.5CFM with air pressure 1.79mm H2O

So basically they pull around the same air and have almost same air pressure.
Is the 0.17mm noticeable at all or not?

//UPDATE:
Taken from thermal bench, thanks for recommending that website. Got my answer.
nLMVmT5.jpg
 
#25 ·
Quote:
Originally Posted by Arengeta View Post

In short:
Shadow Wings aka Silent Wings 2 - 1500RPM 50.5CFM with air pressure 1.62mm H2O
Silent Wings 3 - 1450 RPM 50.5CFM with air pressure 1.79mm H2O

So basically they pull around the same air and have almost same air pressure.
Is the 0.17mm noticeable at all or not?

//UPDATE:
Taken from thermal bench, thanks for recommending that website. Got my answer.
nLMVmT5.jpg
What is your Answer?
 
#26 ·
Quote:
Originally Posted by Arengeta View Post

In short:
Shadow Wings aka Silent Wings 2 - 1500RPM 50.5CFM with air pressure 1.62mm H2O
Silent Wings 3 - 1450 RPM 50.5CFM with air pressure 1.79mm H2O

So basically they pull around the same air and have almost same air pressure.
Is the 0.17mm noticeable at all or not?
Quote:
Originally Posted by doyll View Post

What is your Answer?
Silent wings 3 do move more air through a rad at higher RPM's.
 
#27 ·
Quote:
Originally Posted by Arengeta View Post

Silent wings 3 do move more air through a rad at higher RPM's.
Same fan but different reasons.
If we draw a horizontal line on graph above at 35.3dB we see the Silent Wings 3 moving progressively more air at the same dB sound level at same db as Silent Wings 2. Below the line the db level both Silent Wings have almost identical flow to noise graph lines..

This same marginally different sound to airflow levels below room ambient noise levels (approx 35.3db) and higher flow levels at dsmr or lower sound levels is often seen in fans with higher static pressure ratings.
wink.gif

 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top