[SOLVED] Compatibility Issues????: AIO pump and MOBO

Sep 10, 2019
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Solution
You CAN and SHOULD plug that 3-pin female fan connector from the PUMP unit of this system to the mobo CPU_FAN header. It will fit on, but it won't use Pin #4 of the header.

The CPU_FAN header has several functions, not just fan power and speed. In this AIO system, almost all of those are taken over instead by the Corsair iCue software you must download and install. It uses the cable you connect from the pump unit to a mobo USB2 header to communicate with the H100i system. But there is one function that still is left to the mobo CPU_FAN header because it is fast at this. That is monitoring the speed signal it gets (in this case, from the PUMP of the H100i system) for FAILURE - that is, no speed. If that happens MOST mobo CPU_FAN headers...

Paperdoc

Polypheme
Ambassador
You CAN and SHOULD plug that 3-pin female fan connector from the PUMP unit of this system to the mobo CPU_FAN header. It will fit on, but it won't use Pin #4 of the header.

The CPU_FAN header has several functions, not just fan power and speed. In this AIO system, almost all of those are taken over instead by the Corsair iCue software you must download and install. It uses the cable you connect from the pump unit to a mobo USB2 header to communicate with the H100i system. But there is one function that still is left to the mobo CPU_FAN header because it is fast at this. That is monitoring the speed signal it gets (in this case, from the PUMP of the H100i system) for FAILURE - that is, no speed. If that happens MOST mobo CPU_FAN headers take quick action to send you (on screen, and maybe with a beep tone) a warning of that failure. Many, but not all, also take further action to shut down the system quickly without even waiting for the CPU chip's internal temperature sensor to report high temps. This is to protect it from rapid overheating and damage if there is no cooling. SOME such systems even will refuse to start up the system if there is no "CPU_FAN speed" signal. The single connection from the Pump to the CPU_FAN header feeds that pump speed signal to that header so it can be monitored this way. But for all the other functions like provision of power, measuring fan speeds and controlling them, the iCue software takes over.
 
Solution
Sep 10, 2019
19
1
25
You CAN and SHOULD plug that 3-pin female fan connector from the PUMP unit of this system to the mobo CPU_FAN header. It will fit on, but it won't use Pin #4 of the header.

The CPU_FAN header has several functions, not just fan power and speed. In this AIO system, almost all of those are taken over instead by the Corsair iCue software you must download and install. It uses the cable you connect from the pump unit to a mobo USB2 header to communicate with the H100i system. But there is one function that still is left to the mobo CPU_FAN header because it is fast at this. That is monitoring the speed signal it gets (in this case, from the PUMP of the H100i system) for FAILURE - that is, no speed. If that happens MOST mobo CPU_FAN headers take quick action to send you (on screen, and maybe with a beep tone) a warning of that failure. Many, but not all, also take further action to shut down the system quickly without even waiting for the CPU chip's internal temperature sensor to report high temps. This is to protect it from rapid overheating and damage if there is no cooling. SOME such systems even will refuse to start up the system if there is no "CPU_FAN speed" signal. The single connection from the Pump to the CPU_FAN header feeds that pump speed signal to that header so it can be monitored this way. But for all the other functions like provision of power, measuring fan speeds and controlling them, the iCue software takes over.

Thank you for responding!

The CPU_FAN and AIO_Pump Header Pin grid respectively: (left to right)

CPU FAN PWM
CPU FAN IN
CPU FAN PWR
GND

CPU FAN PWM
CPU FAN IN
AIO PUMP PWR
GND

As the female fan connector will not connect to pin#4 will it affect performance or damage the board in the case of a short? As it is not grounded?
 

Paperdoc

Polypheme
Ambassador
Well, you don't want that unused pin to be grounded, but that is not likely to happen unless you have bare wires floating around. Beyond that, leaving it not connected to anything has NO impact on your system. That pin carries what is called the PWM signal used by a 4-pin fan to control its speed, but the mobo really does not care whether that signal is connected to anything or used. In fact, IF the header is used to power AND control a fan as is the basic intention, the header does NOT use the actual fan speed (read from the signal sent back to it from the fan on Pin #3) at all. Based on the internal temperature of a sensor inside the CPU chip, the CPU_FAN header manipulates the signals sent to its fan to change its speed according to the temperature, but it really does NOT care what the speed actually is. It only pays attention to its TEMPERATURE sensor. But when you use the H100i system or similar, even those fan control processes by the mobo header are NOT used, and the Corsair iCue software does that job.