InfernalDragon

Junior Member
Jul 19, 2018
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0
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I've discovered that my motherboard has pwm fan control on the cpu fan header only. The other fan headers control them via voltage. As such my case fans have higher minimum speeds. I would like to know if there is a controller that provides true pwm control over fans or failing that the best way to connect them all to the cpu fan header. My main aim is to reduce the speed of the fans to make the system run quieter.

Mobo is a GA-Z170X-UD5 TH (rev1.0)
Cooling is a NH-D15 (with both fans connected to the cpu fan header via splitter) and 3 NF-A14 PWM ( 2 intake front, 1 exhaust back).
 
Last edited:

Batboy88

Member
Jul 17, 2018
72
2
11
Yeah that was an issue for a long while..then a lot started making all the Headers pwm...then started selling less pwm fans...and I just really hate airrr again after that D14 that was literally been on everything and had a whistle Roar to it with a Delta on it lol.

So yeah tired of hearing that crap..all Loop...and next gpu will be part of it too whatever I get.
 

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
Even though they are 4 pin does not mean they are pwm. If you go to the NF-A14 PWM faq page there is a section which explains the differences.
I'm certain they are all PWM, but you definitely don't have to listen to me.
 

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
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Looking at the manual only the CPU-FAN header is pwm. The others have vcc on the 4th pin which means they are voltage controlled.
It's not necessary to try to change my mind. It's your board, not mine. I'm still certain they are PWM, all but the 3 pin, from my reading of the manual. It's entirely possible that I am wrong.

This is what I see in the manual, which leads me to believe they are PWM and that you can set them up that way. They can also be voltage controlled:

SYS_FAN1/2/3:
Pin No. Definition
1 GND
2 Speed Control
3 Sense
4 VCC


Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 1st System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.

Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 2nd System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.

Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 3rd System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.
 

InfernalDragon

Junior Member
Jul 19, 2018
5
0
6
It's not necessary to try to change my mind. It's your board, not mine. I'm still certain they are PWM, all but the 3 pin, from my reading of the manual. It's entirely possible that I am wrong.

This is what I see in the manual, which leads me to believe they are PWM and that you can set them up that way. They can also be voltage controlled:

SYS_FAN1/2/3:
Pin No. Definition
1 GND
2 Speed Control
3 Sense
4 VCC


Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 1st System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.

Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 2nd System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.

Fan Speed Percentage
Allows you to control the fan speed. This item is configurable only when 3rd System Fan Speed Control
is set to Manual. Options are: 0.75 PWM value /oC ~ 2.50 PWM value /oC.
Not trying to change your mind. Speed control just means it's capable of adjusting the speed. PWM fan headers will always supply a full 12v on the second pin and have speed control on the 4th pin. If there is speed control on the second pin then that means it adjusts the speed by controlling the voltage, unlike pwm which controls the speed by turning the power going to the fans on and off in quick succession. Because of this fact pwm controlled fans can have lowers speeds than voltage controlled ones.

My main aim is to reduce the amount of noise made by the system when it isn't being used for gaming. Although it is the exhaust fan that is responsible for the most of the noise output which I discovered when I temporarily set its rpm to zero. I guess I could take out the exhaust fan, although I don't think this would be a good idea when I'm gaming and the components are giving off more heat.

BTW looking about on other forums there are several other Gigabyte boards which have non pwm 4 pin headers. Not sure about other motherboard manufacturers.
 

UsandThem

Elite Member
May 4, 2000
16,068
7,380
146
I have this board, and it's true there's only one true PWM connector on it.

That said, I didn't have any issues getting the fans that were plugged into the "faux" PWM headers to have any issue controlling them, it's just done a little differently than a true PWM header. Once they released the F20 BIOS, they added the ability to do custom fan curves within the UEFI, and there was really no practical difference between them.
 

InfernalDragon

Junior Member
Jul 19, 2018
5
0
6
I have this board, and it's true there's only one true PWM connector on it.

That said, I didn't have any issues getting the fans that were plugged into the "faux" PWM headers to have any issue controlling them, it's just done a little differently than a true PWM header. Once they released the F20 BIOS, they added the ability to do custom fan curves within the UEFI, and there was really no practical difference between them.
Problem is with voltage control I can't get the fans rpm as low as I could if they were on PWM. The NF-A14 can go as low as 300 RPM on PWM and try as I might I can't get the fans to below 600 on voltage without them turning off, no matter how much i try to set the curve in the bios.
 

UsandThem

Elite Member
May 4, 2000
16,068
7,380
146
Problem is with voltage control I can't get the fans rpm as low as I could if they were on PWM. The NF-A14 can go as low as 300 RPM on PWM and try as I might I can't get the fans to below 600 on voltage without them turning off, no matter how much i try to set the curve in the bios.

True, but for the average user, this isn't an issue. I run my Noctua fans starting around 600 RPM, which these "faux" PWM headers can easily do that. But if a person wants to run their fan at extreme minimum RPMs, then it could be an issue if it's not a true PWM header. But for 99.9% of the people out there, it really won't affect them at all.

In fact, the issue I had with the board was I used Gigabyte's Windows fan utility, and it worked great until they broke it "upgraded" it. After that, I couldn't manually control my fans at all until they added the fan profile in the UEFI starting with the F20 BIOS update (which broke other stuff like overvolting the CPU).
 

ClockHound

Golden Member
Nov 27, 2007
1,108
214
106
Could use a PWM Hub. The Silverstone Hub provides 8 PWM fan headers controlled from one PWM MB header. And 12V from the PSU. Used it in a few builds - CPU PWM fan control of intake fans is the quietest method I've found. The Noc A15 intakes spin down to 300 at idle.

The Swiftech 8 fan hub is good too.
 
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aigomorla

CPU, Cases&Cooling Mod PC Gaming Mod Elite Member
Super Moderator
Sep 28, 2005
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+ 1 to clockhound.

I use those Silverstone hubs for my builds.
They are great, it has a main control sense line where u can plug into the pwm header, and the power is fed via sata power plug.
The splitter also has a capacitor for when you stack it with 8 fans, it has enough current draw capacity.
 

VirtualLarry

No Lifer
Aug 25, 2001
56,226
9,990
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PWM fan headers will always supply a full 12v on the second pin and have speed control on the 4th pin.
That was my understanding as well. Looks like Gigabyte is using a "Fake PWM" - compatible with PWM pinouts, but using voltage to control the fan.
 

mindless1

Diamond Member
Aug 11, 2001
8,028
1,440
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Because of this fact pwm controlled fans can have lowers speeds than voltage controlled ones.
Frankly the difference isn't very important. A fan at 300 RPM might as well not be spinning, that's how little difference there is in the airflow compared to the same sized fan hole without the fan running, when you have other fans too, to move air around, unless you had tried to perfectly match intake with exhaust rate, except in your case the exhaust fan is loudest.

My main aim is to reduce the amount of noise made by the system when it isn't being used for gaming. Although it is the exhaust fan that is responsible for the most of the noise output which I discovered when I temporarily set its rpm to zero. I guess I could take out the exhaust fan, although I don't think this would be a good idea when I'm gaming and the components are giving off more heat.

I wouldn't do without the exhaust fan. That's really the only fan you need when not gaming besides minimal PSU fan RPM. A 2W resistor in series with the fan lead might resolve this, a 3 cent part, only catch is experimentation "may" be needed to arrive at the right ohm value. That value tends to be somewhere between 47 and 120 ohms. The faster the fan's 12V speed, the lower the ohm value you need (somewhat counter-intuitive).

What is it about your system that makes 600RPM noisy? Stamped-out case wall fan grills causing turbulence? Fans I have at 600 RPM I can't even hear, though I usually have systems under the desk rather than on top of it.