iCUE H150i Elite Capellix has 3-pin CPU_FAN connector; Z90 AORUS PRO motherboard only has 4-pin connectors

[efg2]

iCUE documentation says "Connect the pump tach cable to the CPU_FAN header of your motherboard".  But the connector has 3-pins and the mother board only provides 4-pin connections.  The Corsair article or video does not address this problem (https://help.corsair.com/hc/en-us/articles/360049921791-How-to-Install-the-iCUE-Elite-Capellix-liquid-CPU-cooler-for-Intel-sockets ). The video shows a caption "Connect Pump tach Cable to CPU Fan Header on Motherboard".  

This solution seems promising but the iCUE connector blocks the suggested connection on my motherboard: 
https://www.howtogeek.com/273575/what-is-the-difference-between-three-and-four-pin-cpu-fans/

Similar 3-pin/4-pin CPU_FAN questions can be found online, but I'm not seeing one that I think is "definitive" for iCUE H150i.  

Why doesn't Corsair address this issue in documentation, or at least online?  Or a single page that describes the Corsair 3-pin connectors when many motherboards only have 4-pin connections?

Can anyone offer advice?

[DevBiker]

3 pin fan connectors can always connect to 4-pin fan headers. It's not an issue and never has been. And most (but not all) 4-pin fans can connect to (and be controlled by) 3-pin headers as well (DC-control, not PWM).

If you really want, it's super-easy to remove the pin from the 3-pin connector and put it into a 4-pin connector. You can get the housings pretty inexpensively too (shipping will cost more, tbh). But that really wouldn't matter and would have absolutely no impact on functionality at all.

[efg2]

Thank you for your reply.

"can always connect" :  Not always.  My 3-pin connector is blocked from connecting horizontally by design with the 4-pin male connector  (see picture below). The design of the plastic blocks the connection on the AORUS PRO motherboard.

"It's not an issue":  Google show others with the same question, usually with answers that are not  clear.  Some of these questions are years old.  Perhaps you have too much experience?  This is only my 3rd build.

But I noticed there's only one wire connected in the 3-pin connection.  Why would Corsair use a 3-pin connector to connect one wire?  What is the one wire doing from the iCUE H150i pump connecting with CPU_FAN?  What if I don't make any connection?

I noticed If I rotate the 3-pin connector I can get one pin to connect vertically on the left of the 4-pin horizontal connector.  The one pin connecting is pin 4, PWM Speed Control, according to the Z690 AORUS PRO User's Manual.  But that Gigabyte documentation also says the black wire is GND, and the Corsair single wire is black.  But it would seem to make sense this might be PWM Speed Control.

In the picture below the 3-pin connector is vertical and the 4-pin connection is horizontal.  Notice the plastic along the top that blocks a horizontal  connection..  The picture shows the single-wire connection, with the other 3 horizontal pins on the male connector are not used..  (The bottom two female connections on the vertical 3-pin connector are also not used.)

This is the only issue I must resolve before I can power on my new system and start testing.  I guess I could take the chance that the only way the connection can be made might be right?

The 3-pin graphic in the Corsair documentation is TOTALLY WRONG for my mother board.  What's good is documentation when it's wrong?

[LeDoyen]

it's the speed reading signal from the pump, it's not meant to be connected into the PWM output from the motherboard.

Just plug it normally, or you won't get any speed reading on your board, and be greeted with a "CPU fan error" message and a barrage of alarm beeps 🙂

The plastic clip is here in the same place on 3 and 4 pin headers to make sure you don't have to guess which wire goes where.

Edited December 31, 2021 by LeDoyen

[Gnasher McNashFace]

Having (literally yesterday) built a system using the elite cappelix 150i and an ASUS ROG B550-E motherboard combo, I can confirm that you plug the 3 pin tach wire from the AIO into the 4 pin socket on the motherboard. All you have to do is make sure the tab sticking out of the socket lines up with the recess in the plug.

Edit - it's not plugged into the AIO pump header, it's plugged into the CPU fan header, that's just the way the board is labelled as the header to the right is the AIO pump connector (unused with a corsair AIO).

Edited December 31, 2021 by Gnasher McNashFace
Added information.

[c-attack]

The entire purpose of the connector shape is so it can only fit on the motherboard connector one way. Never force it. It should slide on/off easily. 
 

Corsair can’t anticipate what motherboard you will use or make specific install guides for the hundreds of different models. However, as mentioned above the entire purpose of that tachometer wire is to respond to the CPU fan header request for a signal when you boot. The motherboard does not want you to boot without a cooling method in place. This tells the board there is one. Ignore the AIO fan header. That is for a cheaper type of cooler that needs to get power from the motherboard. Your unit does not and their is no motherboard control over any aspect of the AIO. Your cooler will always run when it has the SATA power connector hooked up, with or without that tachometer cable. It’s the motherboard’s safety feature that is being satisfied.