Fans running at full speed even with PWM fan splitter

[iddra7]

A couple weeks ago I made a post asking how to connect multiple fans to one system fan header and not have them run at full speed.

http://www.tomshardware.co.uk/answers/id-3731870/connecting-multiple-fans-single-fan-header.html

Gigabyte GA-B250M-DS3H
4 x 3 pin fans

Eventually I found this:
https://www.aliexpress.com/item/45cm-Fans-Extension-Power-Cable-Connector-4-Pin-Molex-Fan-Power-Cable-5x-PWM-4Pin-Fan/32849805448.html

It has 4 x 3 pins and 1 x 4 pin connector, the motherboard connector and a molex for power.

I now have all 4 fans connected and they're all running at full speed. I changed the control method to voltage in the BIOS, but none of the settings do anything. At least I can see the speed, which is something, I guess.

I disconnected the molex and none of them run, I guess they all get power exclusively from the molex.

I plugged one fan into the system header and it runs as expected, so that's not the issue.

I also tried to plug the CPU fan, which has 4 pins, into the cluster (maybe I have to use a 4 pin fan) but that still doesn't work.

At this point I don't know what to do.

Also, the 3 pin connectors I bought seem kinda weird, only 2 pins actually connect to the fan.

 

[why_wolf]

that won't work with 3 pin fans. Despite what that picture shows. What it's really doing is saying it will group a series of 4 pin fans based of the speed off one master 4 pin fan.

3 pin fans are controlled by voltage level. If your case has an external 5.25" drive slot you can use a fan controller like this. https://www.newegg.com/Product/Product.aspx?Item=9SIAAXT55G4191

This might work as well. https://www.newegg.com/Product/Product.aspx?Item=9SIACJF6V67929&cm_re=3_pin_fan_splitter-_-9SIACJF6V67929-_-Product

Ultimately you should have gone with 4pin fans and this https://www.amazon.com/SilverStone-System-Cables-Black-CPF04/dp/B00VNW556I

 

[iddra7]

that won't work with 3 pin fans. Despite what that picture shows. What it's really doing is saying it will group a series of 4 pin fans based of the speed off one master 4 pin fan.

3 pin fans are controlled by voltage level. If your case has an external 5.25" drive slot you can use a fan controller like this. https://www.newegg.com/Product/Product.aspx?Item=9SIAAXT55G4191

This might work as well. https://www.newegg.com/Product/Product.aspx?Item=9SIACJF6V67929&cm_re=3_pin_fan_splitter-_-9SIACJF6V67929-_-Product

Ultimately you should have gone with 4pin fans and this https://www.amazon.com/SilverStone-System-Cables-Black-CPF04/dp/B00VNW556I

How will it group 4 pin fans when it only has 1 x 4 pin connector?

 

[Paperdoc]

Some of the answers in your earlier thread were wrong. The post above from why_wolf is correct. I don't think the Enlabs product in the first link would do what you want - it only allows you MANUAL control of your fans. Although you started out saying you were looking for full speed on all four case fans, you have changed to wanting them under automatic control by the mobo. Unfortunately, based on the earlier thread, it appears you bought 3-pin fans and they won't work with most fan Hubs.

Some background to help understand. First, don't focus so much on matching the pin counts on the device you buy for connecting multiple fans together. Do focus on the number of wires from a fan motor, and hence on the number of holes in the female connector on their end. There are 3-pin fans and 4-pin fans, and they each require the mobo header to use a different Mode of control for them. 3-pin fans can be controlled only by Voltage Control Mode (aka DC Mode) in which the voltage to the fan on Pin #2 varies from 12 VDC (max speed) down to about 5 VDC (min speed without stalling). 4-pin fans can be controlled with such a signal, but are controlled better by the new PWM Mode. In this system, the fan receives a constant 12 VDC on Pin #2 (never reduced) PLUS it gets the new PWM signal from Pin #4. Inside the fan there is a small chip that uses the PWM signal to alter the power from the fixed 12 VDC supply and achieve speed changes. If these PWM Mode signals are sent to a 3-pin fan, it always gets the full 12 VDC on Pin #2 and always runs full speed. It does not get the PWM signal from Pin #4 - it has no connection to that - and it could not use it, anyway, because it has no chip to do that.

Hubs and Splitters are two different types of device for many fans together on one header. But both have one important thing in common. Almost all fans generate a speed signal it sends to the mobo header on Pin #3, BUT the header can only deal with ONE speed signal coming it to count. So the Hub or Splitter will only send to the header the speed signal from ONE of its fans and ignore the rest. The most common way to do this is simple, and is what you have seen on your device. ONE of the male (with pins) output connectors has all its pins, but all the other outputs are missing Pin #3 so those fans cannot send their speed signals to the mobo header. This does NOT make that one output the Master! It means simply that ONLY that one fan's speed can be "seen" by the mob header and displayed for you. The lack of a speed reading from the other fans has NO impact on achieving speed control of them all.

That Ali Express device you bought is a HUB, and this is how it works to supply power to many fans without overloading the mobo header AND to exert control over the speed of them all. You see that there is one 4-pin Molex connector to a PSU output, and this is the source of all power to all the fans - note it has TWO wires to each of the four output connectors for this. Now look closely at the 4-pin female fan connector that plugs into the mobo SYS_FAN header. You will see also that it does NOT have any connections from Pins 1 and 2 of the mobo header to any of the output headers. It connects Pin 3 to only ONE of the output connectors (labelled 4-pin) so that the speed of that fan only can be sent back to the mobo. And then it connects from Pin 4 of the mobo header to the Pin 4 positions of ALL of its output connectors. This is how it distributes the PWM control signal from the mobo to all the fans. So, this Hub provides POWER from the PSU ONLY (not the mobo header) to all fans, provides the CONTROL (PWM) signal from the mobo to all four fans, and returns to the mobo the speed signal from ONE fan.

This Hub device can only work with a mobo header that actually does work in PWM Mode to supply the PWM signal required - hence, you MUST set that mobo header to use PWM Mode, and NOT Voltage Control Mode. Just as importantly, ALL of the fans connected to it MUST be of the 4-pin type that includes the special chip inside to use that PWM signal to control itself. You can NOT control the speed of 3-pin fans using this system!

So, you have two possible solutions for your situation. One is to replace the 3-pin fans you have with 4-pin models, and they WILL be controlled by this system provided you configure your SYS_FAN header to use PWM Mode. The other is to replace that Ali Express Hub device with a unique different Hub, the Phanteks PWM Hub. It is a box that does a VERY similar job but with an important change. It does not simply send the PWM signal from the mobo header out to the fans and expect them to use that. Instead it uses the PWM signal internally to create its own group of six 3-pin fan headers that use Voltage Control Mode, and hence CAN control the speeds of 3-pin fans. It has only 3-pin fan output headers. So, you CAN use this Hub with a mobo header operating in PWM Mode, but it will control 3-pin fans just fine. Now, such an output also can be used with 4-pin fans, so IF you have any 4-pin fans you are using on the Hub for case ventilation, it can be done. BUT there's a tiny glitch to watch for. The slots on the side of this Hub are probably too narrow to allow you to fit a 4-pin fan female connector onto the output pins of a port. And, there IS a solution to this, too! The Hub comes with two little Splitters intended to allow you to connect two fans to a single output port of the Hub. But using one of these on an output port will give you two male output connectors that have no shroud around them, so you CAN plug a 4-pin fan into one of them and it works.

Either of those two changes will get you control of the speed of all the case fans from that single mobo SYS_FAN header. Your choice.

 

[iddra7]

So, you have two possible solutions for your situation. One is to replace the 3-pin fans you have with 4-pin models, and they WILL be controlled by this system provided you configure your SYS_FAN header to use PWM Mode. The other is to replace that Ali Express Hub device with a unique different Hub, the Phanteks PWM Hub. It is a box that does a VERY similar job but with an important change. It does not simply send the PWM signal from the mobo header out to the fans and expect them to use that. Instead it uses the PWM signal internally to create its own group of six 3-pin fan headers that use Voltage Control Mode, and hence CAN control the speeds of 3-pin fans. It has only 3-pin fan output headers. So, you CAN use this Hub with a mobo header operating in PWM Mode, but it will control 3-pin fans just fine. Now, such an output also can be used with 4-pin fans, so IF you have any 4-pin fans you are using on the Hub for case ventilation, it can be done. BUT there's a tiny glitch to watch for. The slots on the side of this Hub are probably too narrow to allow you to fit a 4-pin fan female connector onto the output pins of a port. And, there IS a solution to this, too! The Hub comes with two little Splitters intended to allow you to connect two fans to a single output port of the Hub. But using one of these on an output port will give you two male output connectors that have no shroud around them, so you CAN plug a 4-pin fan into one of them and it works.

Either of those two changes will get you control of the speed of all the case fans from that single mobo SYS_FAN header. Your choice.

Thank you very much for the explanation.

Do I have to buy a boxed hub? I'd have to buy extension cables as well. Does a hub with just wires exist, then they'd use the DC method from the mobo.

I don't need to manually control them, I just don't want them running at full speed.

edit: So I guess I'm looking for a 3 pin splitter, not a hub?

Okay, so if I have to buy a boxed hub, I might as well get a physical fan controller?

https://www.ebay.com/itm/6-Channel-Fan-Speed-Controller-Front-Panel-CPU-Temperature-Sensor-for-PC-Desktop/123215551310?epid=22020168327&hash=item1cb0381b4e%3Ag%3APlgAAOSwsEhbFlh-&_sacat=0&_nkw=fan+controller&_from=R40&rt=nc&LH_TitleDesc=0

Would something like this work?

 

[Paperdoc]

Well, the "boxed" design of Hub is not necessary. But the only design of that Phanteks PWM Hub available is a closed box with ports along 2 sides, and that is the only Hub that does the "conversion" from 4-pin PWM Mode to 3-pin Voltage Control Mode. You need that for controlling your 3-pin fans. I can understand that, depending on the layout of your case and fan locations, you might need simple fan extension cables to reach from one or more fans to the Hub at a particular location. The Hub can be placed anywhere in your case.

A SPLITTER as an alternative is possible IF you verify that one important limit is met. The single SYS_FAN header on your mobo can supply up to 1.0 A max current to the total load of all the fans connected to it using a Splitter. So, look up the specs of those case fans you have. If you need help with that, post back here the maker and model number of the fans, and we can help. I suspect the four are all the same units. So, IF each of those fans consumes at max less than 0.25 A, then yes, a Splitter can do the job.

Why is this important? A SPLITTER is a simpler device than a Hub. It simply connects all of its outputs (hence, all its fans) in parallel to the power supplied from the mobo header on Pins 1 and 2, so all power AND control of the fans is done solely by the mobo header. As I said earlier, it also ensures that only one fan's speed signal is sent back to the host header.

The design of 3-pin and 4-pin fan wiring and connectors allows for complete mixing of connections, although with some results not quite what you might want. So you CAN plug any 3-pin OR 4-pin fan into any 3- pin OR 4-pin header or output connector and it will work. The major mis-match result is when you plug a 3-pin fan into a 4-pin source that actually is using PWM Mode. That one combination results in the fan running full speed always with no control. SO, you may find that it is hard to find a 3-pin fan Splitter, but any 4-pin fan Splitter will do exactly the same job and will fit. The mis-match factors are linked solely to the way the header controls the fans, and not to the Splitter itself.

It's hard to find a Splitter with four outputs. But there's a simple way to make one. Get three of this type which has two outputs.

https://www.newegg.com/Product/Product.aspx?Item=N82E16812423161&cm_re=coboc_fan_splitter-_-12-423-161-_-Product

Plug two of them into the output arms of the third. The resulting stack gives you four outputs from a single input. That model has 12" arms, so the stack will give you lots of reach around your case if you need it. This is by far the simplest (and low-cost) way to connect four 3-pin fans to a single mobo header that can power them AND provide automatic control of their speeds, provided the total load of the fans is no more than 1.0 A.

I doubt a third-party Fan Controller module mounted in your case front will do what you want. First item is cost. The one you linked from an eBay seller costs nearly US$22 and ships free from Hong Kong arriving in maybe a month. You can buy a Phanteks PWM Hub from Newegg for US$16 with free shipping delivered in about 1 week in the USA, or pay a $5 more for faster shipping.

https://www.newegg.com/Product/Product.aspx?Item=9SIA4RE5032993&cm_re=Phanteks_PWM_Hub-_-11-984-004-_-Product

A Fan Controller module in your case front still has the issue that it is a centralized location, although that particular one you linked to has outputs on the ends of cables of some unknown length. Using a controller like that you never will see ANY of the fans' speeds, although that is not important to many. And of course, that controller allows you to set all fan speeds manually with no possibility of automatic control. That also means it is up to YOU to monitor your system temperatures in several places and adjust the fans' speeds to ensure adequate cooling as your workload changes.

 

[iddra7]

A Fan Controller module in your case front still has the issue that it is a centralized location, although that particular one you linked to has outputs on the ends of cables of some unknown length. Using a controller like that you never will see ANY of the fans' speeds, although that is not important to many. And of course, that controller allows you to set all fan speeds manually with no possibility of automatic control. That also means it is up to YOU to monitor your system temperatures in several places and adjust the fans' speeds to ensure adequate cooling as your workload changes.

The fans are rated at 0.2 A, which is fine.
I'll probably buy 3 splitters.
Seems like the eBay controller would also work. The cables are 2 feet long. I can see 3 pins inside the connectors...

So would the eBay controller also work? I'm just making sure.

 

[Paperdoc]

Yes, the eBay controller will work. It won't give you any automatic control, and you will not "see" any fan speeds at all from your case fans. But it certainly will give you power and manual speed control of your fans. In fact, each fan can be manually controlled individually and separately from the others on that Controller.

 

[iddra7]

Yes, the eBay controller will work. It won't give you any automatic control, and you will not "see" any fan speeds at all from your case fans. But it certainly will give you power and manual speed control of your fans. In fact, each fan can be manually controlled individually and separately from the others on that Controller.

Okay, thank you very much for helping me.

 

[Paperdoc]

You're welcome, and thanks for Best Solution.