CPU_FAN only PWM header on Mobo.

[aciddrago]

Recently I have discovered that the case fan headers on my motherboard are voltage controlled not pwm controlled. Because the case fans are voltage controlled they are not able to spin slower than they would if they were pwm controlled. I am wondering if there is a fan controller that would provide me pwm control over the case fans or a splitter/hub that would allow me to connect them all to the cpu fan header.

Specs:
GA-Z170Z-UD5 TH (rev 1.0)
I7-6700K
EVGA 1080 FTW
NH-D15 with both fans connected via splitter to the cpu fan header
3x NF-A14 PWM(2 front intake, 1 back exhaust)

Edit with additional info
The front fan are connected to SYS FAN 1-2 and the back fan is connected to SYS FAN 3
All Fan headers are set to the silent fan profile in the bios. I was using EVGA's SIV software to control the fans but uninstalled it after I discovered I could get lower speeds by just letting the bios handle it.
Also, while the bios does allow custom fan curves, it handles the non pwm headers differently to the pwm one (SYS Fan 4 is not there). The pwm one has a 4 point curve while the none pwm ones have only 2 points.
The reason I want the case fans to be pwm controlled is so I can have lower speeds (The NF-A14 can spin at a minimum of 300 RPM on PWM control, voltage control has a higher minimum RPM). I have discovered the NZXT GRID+ V3 and the Corsair Commander Pro which seem like they could do the job and allow separate control of each fan but the problem is there are no usb ports on the motherboard itself (unless there are pcie cards with internal usb ports that I could use).

 

[JuniperSprouts]

Unless you live in a hot environment, you should just get a splitter and have low RPM fans.

What you want is definitely available: https://www.newegg.com/Product/ProductList.aspx?Description=FAN%20CONTROLLER&Submit=ENE

If you are using high powered fans, you will want to get a controller that gets power from molex (or some other 12v from the PSU), becaue the fan headers are only rated for so much amperage (power draw).

 

[Paperdoc]

Noctua does not have a fan NH-A14, but I suspect you just mis-typed that. The do have several NF-A14 models 3-pin and 4-pin. Since you say "Because the case fans are voltage controlled they are not able to spin slower than they would if they were pwm controlled", I have to assume they are 3-pin fans, either their NF-A14 FLX or the slower / quieter NF-A14 ULN. Is that correct? Can you confirm these three all are 3-pin fans with 3 wires from their motors to their connectors?

Now, you are right about the mobo SYS_FAN1 and ...2 and ...3 headers - they are labelled to use only the older Voltage Control Mode. BUT watch out for the SYS_FAN4 header. It is different - it does NOT do any control, and supplies a fixed full 12 VDC to its fan(s). So IF you have any fan plugged into that header, that is why it always runs full speed.

It really does not matter whether your fans are 3-pin or 4-pin. The backwards compatibility features of the new 4-pin fans mean that they also CAN have their speed controlled by a mobo header using Voltage Control Mode. So, all of those three case fans, regardless of their type, should be controllable by the SYS_FAN1 or ..2 or ..3 headers. Do NOT use the SYS_FAN4 header.

You have not told us where those three case fans are plugged in. IF they are on those SYS_FAN headers (except 4) their speeds should be under control. On the other hand, if you have arranged somehow to connect them to either SYS_FAN4 or CPU_FAN headers, AND it they are 3-pin fans, then they always will run full speed and you need to change their connection header.

The max current of these fans is low, from 0.04 A to 0.13 A, so it is entirely OK to connect three such fans to a single mobo SYS_FAN header using a splitter system. But you don't need that since you have three capable SYS_FAN headers to use.

Let us know more details about the fan type (3 or 4 wires / pins) and the headers you have them plugged into. You also should check the configuration of those headers to ensure they are set to use the automatic "Normal" control profile.