Different fans, same splitter.

[Watashi]

I have two different sets of fan hooked up too a 5 way PWM splitter. And I'm attempting to use PWM control through my BIOS to manage fan speeds. It doesn't seem to be working, I was wondering if this may be because 3 fans are Noctua NF-12s and the other are 2 Noctua P14s. Any thoughts on this?

[For Science!]

1 hour ago, Doomerson said:

I have two different sets of fan hooked up too a 5 way PWM splitter. And I'm attempting to use PWM control through my BIOS to manage fan speeds. It doesn't seem to be working, I was wondering if this may be because 3 fans are Noctua NF-12s and the other are 2 Noctua P14s. Any thoughts on this?

Which motherboard are you using and which header are you plugged into? some motherboards only have genuine PWM headers on some headers (usually CPU_FAN)

 

Also a link to the exact splitter you are using would be helpful

[Biggerboot]

6 hours ago, Doomerson said:

I have two different sets of fan hooked up too a 5 way PWM splitter. And I'm attempting to use PWM control through my BIOS to manage fan speeds. It doesn't seem to be working, I was wondering if this may be because 3 fans are Noctua NF-12s and the other are 2 Noctua P14s. Any thoughts on this?

Have you tried seeing if it works with just one type of the fans?  Is it just PWM that's not working?

My first guess would be that they're just not getting enough power being split five ways from a single onboard connection.

[Watashi]

11 hours ago, For Science! said:

Which motherboard are you using and which header are you plugged into? some motherboards only have genuine PWM headers on some headers (usually CPU_FAN)

 

Also a link to the exact splitter you are using would be helpful

MSI Z170 gaming m5. And I had no idea genuine PWM headers were only found on the cpu-fan ports. wow. And honestly I don't even recall the splitter I was using

[Watashi]

6 hours ago, Biggerboot said:

Have you tried seeing if it works with just one type of the fans?  Is it just PWM that's not working?

My first guess would be that they're just not getting enough power being split five ways from a single onboard connection.

That's possible, but there is also a molex plug supplying power to the fans. And they seem to be spinning full speed. They are appearing on my hardware monitor within UEFI, and are apparently running at full speed.  

[For Science!]

2 hours ago, Doomerson said:

MSI Z170 gaming m5. And I had no idea genuine PWM headers were only found on the cpu-fan ports. wow. And honestly I don't even recall the splitter I was using

Just checked page 40 of your motherboard manual. Only CPUFAN1 and CPUFAN2 are PWM headers. All SYSFAN headers are only voltage control (although being 4-pin)

[Biggerboot]

8 hours ago, Doomerson said:

That's possible, but there is also a molex plug supplying power to the fans. And they seem to be spinning full speed. 

Also a molex?  I may be misunderstanding the configuration of the splitter, but molex would make your fans run 100 percent all the time.  Any fans you want to run with PWM will need to be powered strictly off the board.

[Watashi]

11 hours ago, For Science! said:

Just checked page 40 of your motherboard manual. Only CPUFAN1 and CPUFAN2 are PWM headers. All SYSFAN headers are only voltage control (although being 4-pin)

Wow, thanks a lot for the help!

[Watashi]

5 hours ago, Biggerboot said:

Also a molex?  I may be misunderstanding the configuration of the splitter, but molex would make your fans run 100 percent all the time.  Any fans you want to run with PWM will need to be powered strictly off the board.

https://www.newegg.com/Product/Product.aspx?Item=N82E16812311001&ignorebbr=1&nm_mc=KNC-GoogleAdwords-PC&cm_mmc=KNC-GoogleAdwords-PC-_-pla-_-Cables+-+Internal+Power+Cables-_-N82E16812311001&gclid=CjwKCAjwoNrMBRB4EiwA_ODYv8YTmq-Jtk4D-HxLDwUQGETqEdixkACHqIUZWuyMhr-pV-73DB6aKhoCXqcQAvD_BwE&gclsrc=aw.ds

that is the splitter that I'm using.

[Biggerboot]

58 minutes ago, Doomerson said:

https://www.newegg.com/Product/Product.aspx?Item=N82E16812311001&ignorebbr=1&nm_mc=KNC-GoogleAdwords-PC&cm_mmc=KNC-GoogleAdwords-PC-_-pla-_-Cables+-+Internal+Power+Cables-_-N82E16812311001&gclid=CjwKCAjwoNrMBRB4EiwA_ODYv8YTmq-Jtk4D-HxLDwUQGETqEdixkACHqIUZWuyMhr-pV-73DB6aKhoCXqcQAvD_BwE&gclsrc=aw.ds

that is the splitter that I'm using.

Ok.  Disconnect the molex and just plug the 4 pin connector into one of the sysfan ports (it may also be useful to try one of the CPU fan ports if that doesn't work).

[Watashi]

14 hours ago, Biggerboot said:

Ok.  Disconnect the molex and just plug the 4 pin connector into one of the sysfan ports (it may also be useful to try one of the CPU fan ports if that doesn't work).

why unplug the molex? I just assumed that it provided extra power for the fans to work.

[Biggerboot]

12 hours ago, Doomerson said:

why unplug the molex? I just assumed that it provided extra power for the fans to work.

My understanding is that with molex you're either getting full power or no power, so there's no gradient of speed that your fans can work on.  Molex is there as an option (I'm guessing based on experience with fans that have a similar option).  At the same time, I don't know if you'll get enough power from a single motherboard port to power all the fans sufficiently if they're high end fans.  That doesn't make the cable bad, but it's very niche.

Thats why people usually resort to fan controllers in that situation (or you'll want to use something like two 2-way splitters), but try it without the molex first.

[Watashi]

11 hours ago, Biggerboot said:

My understanding is that with molex you're either getting full power or no power, so there's no gradient of speed that your fans can work on.  Molex is there as an option (I'm guessing based on experience with fans that have a similar option).  At the same time, I don't know if you'll get enough power from a single motherboard port to power all the fans sufficiently if they're high end fans.  That doesn't make the cable bad, but it's very niche.

Thats why people usually resort to fan controllers in that situation (or you'll want to use something like two 2-way splitters), but try it without the molex first.

*sighs* Do you think a 3 way splitter would work? That way I could run 3 fans on one rad (360mm) and 2 on the other (240mm). And running the case fans at full speed is fine with me.

 

[For Science!]

20 hours ago, Biggerboot said:

My understanding is that with molex you're either getting full power or no power, so there's no gradient of speed that your fans can work on.  Molex is there as an option (I'm guessing based on experience with fans that have a similar option).  At the same time, I don't know if you'll get enough power from a single motherboard port to power all the fans sufficiently if they're high end fans.  That doesn't make the cable bad, but it's very niche.

Thats why people usually resort to fan controllers in that situation (or you'll want to use something like two 2-way splitters), but try it without the molex first.

 

11 hours ago, Doomerson said:

*sighs* Do you think a 3 way splitter would work? That way I could run 3 fans on one rad (360mm) and 2 on the other (240mm). And running the case fans at full speed is fine with me.

 

PWM control expects a constant 12V and only modulation by the pulse width (hence Pulse Width Modulation, as opposed to voltage control). So I think having the molex connected is fine.

[Biggerboot]

13 hours ago, Doomerson said:

*sighs* Do you think a 3 way splitter would work? That way I could run 3 fans on one rad (360mm) and 2 on the other (240mm). And running the case fans at full speed is fine with me.

 

Any trial and error you could try before buying another cable would help.  I would try adding one fan at a time onto the 5 way splitter and see when/if it stops working.  I could be off the mark in saying it won't give enough power, but IDK how much wattage the fan ports are designed to give.

1 hour ago, For Science! said:

PWM control expects a constant 12V and only modulation by the pulse width (hence Pulse Width Modulation, as opposed to voltage control). So I think having the molex connected is fine.

Right, bare with me because my electronics knowledge is basic, but I understand what PWM is.  It might depend on the way the splitter is wired (or the design of the circuit).  So if the 12v power source from the molex and fan connector are shared (prior to PWM in the circuit), then I could see PWM working regardless.  If they're separate, which I have found to be the case with some fans that have both connectors, it'll just always run full speed.

I'll try to find some examples if I can.