Question Want to switch case fans from 3-pin to pwm/4-pin, unsure how to do that

[Webslinger64]

I recently installed 3 RGB 120mm case fans to my PC. In doing so, I thought now might be a good time to switch them from 3-pin headers to 4-pin headers so I can control fan speed without entering the BIOS each time. The problem I ran into is this - there are 3 120mm case fans (2 on top and 1 in the back) and two 140mm case fans in the front. The motherboard is an AsRock Fatal1ty Z87 Killer and it has two 3-pin chassis fan connectors, one 3-pin power fan connector, one 4-pin chassis fan connector, one 3-pin CPU fan connector and one 4-pin CPU fan connector.
I have the two 140mm case fans on the front of the PC connected to the 4-pin chassis fan connector and the CPU connected to the 4-pin CPU fan connector. For the three case fans I just installed, they are all connected to 3-pin connectors. Not really sure what the best solution is to connect those 3 case fans to a 4-pin connector.
When considering the 4-pin connector that's already used for my front two 140mm case fans, I believe I can get a 4-pin pwm fan splitter that will allow me to add one case fan to that connector. But, that leaves two case fans to deal with. Can I also use a 4-pin pwm fan splitter on the 4-pin CPU connector and then connect the CPU and two case fans to that connector? Is that the simplest solution, or is there a better one?

 

[Paperdoc]

First, I have to presume from your post that the three new fans are 4-pin models, right? Second, you appear to believe you can NOT control any fan's speed from a 3-pin header. WRONG! The ONLY way to control the speed of a 3-pin older fan is to use a 3-pin header, OR to make a 4-pin header behave like a 3-pin one (your mobo does not allow this last). The IDEAL way to control the speed of a newer 4-pin PWM fan is to connect it to a 4-pin PWM header. But you CAN control such a 4-pin fan with a 3-pin header! It's just not quite ideal from a technical perspective. The KEY to this on any header is that you MUST configure it to use the default STANDARD Mode so that it does adjust your fan speeds automatically according to a temperature sensor. See your mobo manual, p.88. After you have set the particular header(s), remember to use Esc back to the Main Menu and then to the Exit Menu (p. 93) and choose Save Changes and Exit to save your new settings and reboot. You can NOT control the speed of a THREE-pin fan from a FOUR-pin header that does PWM control.

Do NOT connect these case ventilation fans to the CPU_FAN header. That header uses as its guide a temperature sensor inside the CPU chip, so it is designed for the CPU cooler system. The CHA_FAN headers are guided by a different temp sensor on the mobo, so that's for all case vent fans.

If you want to do "ideal" control of your new 4-pin fans using the 4-pin PWM Mode of control signals, you should get a fan HUB. This is a device somewhat like a Splitter in that it can connect several fans to one mobo header to share control. A Splitter has one input cable to the mobo header, and several output connectors for fans. But a HUB is different in one special detail. It has an extra connection to a SATA or 4-pin Molex power output connector direct from the PSU. It gets all power for its fans from that PSU and draws none from the host header, so it is NOT limited to a small number of fans. It DOES get the control signal from the host header and return to that header the speed of only ONE of its fans to be read. A Hub may look like a collection of cable arms, like a small circuit board, or like a box with ports in the side. Examples

https://www.amazon.com/XMSJSIY-Adapter-Splitter-Desktop-Computer/dp/B093ST9W5L/ref=sr_1_67?crid=1IHKJFPDLOXO7&keywords=fan+splitter&qid=1679346739&sprefix=fan+splitter,aps,108&sr=8-67

https://www.amazon.com/Fancasee-Splitter-Internal-Motherboard-Extension/dp/B089KDCMDN/ref=sr_1_9?crid=2E1VNWSIFO3UC&keywords=fan+hub&qid=1679346540&sprefix=fan+hub,aps,111&sr=8-9

https://www.amazon.com/ARCTIC-Case-Fan-Hub-Distributor/dp/B0887VG14J/ref=sr_1_16?crid=2E1VNWSIFO3UC&keywords=fan+hub&qid=1679346596&sprefix=fan+hub,aps,111&sr=8-16

In each case, note the unit has one connection to the mobo host CHA_FAN header, one to a PSU power output connector, and several ports to plug in your 4-pin fans. ONE output port (often Port #1) is marked as the only one that sends back its fan's speed.

Using any one of these you could connect from three to ten (depends on the unit you choose) fans to one CHA_FAN 4-pin PWM header so the fans all share the PWM signal.

 

[Webslinger64]

First, I have to presume from your post that the three new fans are 4-pin models, right? Second, you appear to believe you can NOT control any fan's speed from a 3-pin header. WRONG! The ONLY way to control the speed of a 3-pin older fan is to use a 3-pin header, OR to make a 4-pin header behave like a 3-pin one (your mobo does not allow this last). The IDEAL way to control the speed of a newer 4-pin PWM fan is to connect it to a 4-pin PWM header. But you CAN control such a 4-pin fan with a 3-pin header! It's just not quite ideal from a technical perspective. The KEY to this on any header is that you MUST configure it to use the default STANDARD Mode so that it does adjust your fan speeds automatically according to a temperature sensor. See your mobo manual, p.88. After you have set the particular header(s), remember to use Esc back to the Main Menu and then to the Exit Menu (p. 93) and choose Save Changes and Exit to save your new settings and reboot. You can NOT control the speed of a THREE-pin fan from a FOUR-pin header that does PWM control.

Do NOT connect these case ventilation fans to the CPU_FAN header. That header uses as its guide a temperature sensor inside the CPU chip, so it is designed for the CPU cooler system. The CHA_FAN headers are guided by a different temp sensor on the mobo, so that's for all case vent fans.

If you want to do "ideal" control of your new 4-pin fans using the 4-pin PWM Mode of control signals, you should get a fan HUB. This is a device somewhat like a Splitter in that it can connect several fans to one mobo header to share control. A Splitter has one input cable to the mobo header, and several output connectors for fans. But a HUB is different in one special detail. It has and extra connection to a SATA or 4-pin Molex power output connector direct from the PSU. It gets all power for its fans from that PSU and draws none from the host header, so it is NOT limited to a small number of fans. It DOES get the control signal from the host header and return to that header the speed of only ONE of its fans to be read. A Hub may look like a collection of cable arms, like a small circuit board, or like a box with ports in the side. Examples

https://www.amazon.com/XMSJSIY-Adapter-Splitter-Desktop-Computer/dp/B093ST9W5L/ref=sr_1_67?crid=1IHKJFPDLOXO7&keywords=fan+splitter&qid=1679346739&sprefix=fan+splitter,aps,108&sr=8-67

https://www.amazon.com/Fancasee-Splitter-Internal-Motherboard-Extension/dp/B089KDCMDN/ref=sr_1_9?crid=2E1VNWSIFO3UC&keywords=fan+hub&qid=1679346540&sprefix=fan+hub,aps,111&sr=8-9

https://www.amazon.com/ARCTIC-Case-Fan-Hub-Distributor/dp/B0887VG14J/ref=sr_1_16?crid=2E1VNWSIFO3UC&keywords=fan+hub&qid=1679346596&sprefix=fan+hub,aps,111&sr=8-16

In each case, note the unit has one connection to the mobo host CHA_FAN header, one to a PSU power output connector, and several ports to plug in your 4-pin fans. ONE output port (often Port #1) is marked as the only one that sends back its fan's speed.

Using any one of these you could connect from three to ten (depends on the unit you choose) fans to one CHA_FAN 4-pin PWM header so the fans all share the PWM signal.

Fantastic information and a great education for me. Thank you very much for taking the time. I will follow your recommendations and cross this off my to-do list.

Thanks again!

 

[Paperdoc]

You're welcome and good luck!

 

[ReveurGAM]

As a note, make sure that it is an actual hub/controller. There are also relays/repeaters/nodes that also draw power from the PSU but their functionality is limited to what the header can do. An example is the PWM relay in the Corsair iCUE 5000x RGB Case. Even though it has its own power, if your fans exceed the limit of the header, then the BIOS will not register that the node is connected and will not display any fan info for that header, although software in the OS might. I had this experience and overloading can potentially cause damage.