Question Corsair h150i connector question


Feb 3, 2012
I am cooling using the Corsair h150i aio on an Asus Maximus Hero XI board with 9900k cpu.

My question is about the fan connection. I connected it as suggested by the corsair manual, which was to connect the pump to the CPU_FAN header... but the Asus manual suggests using the AIO_PUMP header..

is there a difference, or a preference here?


Corsair and Asus have different opinions. For Corsair, they are banking on the fan living longer than the pump. Cpus have built in security feature that if cpu_fan header reads 0rpm, it'll shutdown the pc or refuse to boot. So Corsair says stick the pump on cpu_fan (just incase the pump fails).
Asus actually wants you to get performance out of their board, that includes a cpu fan that changes according to cpu temp, and a pump that always runs with 100% 12vDC. So they say cpu fans go on cpu_fan header and here's a handy pump header for that purpose.

While Corsair is good at covering its *** with pump on cpu_fan header, realistically you'll find most ppl will prefer their fans to operate with cpu temps, not a constant full velocity, even at idle. So fans on cpu_fan and pump on cpu_aux or cpu_pump header.

With the H150i, there's a 4pin fan connector that goes to the cpu_fan header. This only populates the header to prevent cpu shutdown. Power comes from a dedicated Sata power straight from the psu. Control is by the iCue software and the USB cable. The instructions you have are for the basic AIO's, like the H60, not the advanced AIO's like the H150i.
Actually, Corsair like many other AIO system makers, designs their system so that the pump must receive a constant 12 VDC power supply and run full speed all the time, and all control of cooling the CPU is done by manipulating the speeds of the radiator fans. HOW those design aims are accomplished depends on the AIO system design, so following the instructions for the system you have is important.

Some other systems leave the CPU cooling control to the existing system built into the mobo's CPU_FAN header. That system uses the actual temperature inside the CPU chip as its guide (the case fan system uses a different sensor on the mobo) and varies the cooling fan speed according to that. However, it also has certain control loop "tuning parameters" like Gain and Response Time that are optimized for the default expectation, a FAN on a CPU heatsink. Technically, the correct tuning parameters for an AIO system that is much larger might need to be different, although that is not too critical.But the CPU_FAN header also carries out a second vital function: failure detection. It monitors the fan speed signal it receives and takes rapid action if that ever fails, to protect the expensive CPU chip from overheating. It usually does not even wait for the temperature inside the CPU to get too hot. When the CPU cooler actually is a fan and heatsink, failure of the fan is a sure sign of trouble. But when the cooler system is an AIO system, there is a little more time to react if the RAD FANS fail because the PUMP is still moving heat out to the rad, even though the heat removal there may be poorer. So, very often the makers of the AIO system believe the critical component to monitor for failure is the PUMP, not the fans, and they want that to be the device reporting its speed to the CPU_FAN header.

In the Corsair H150i system, the pump is supposed to operate a full speed all the time. The fan speeds vary. Both components of this cooling system need to be monitored for failure. So Corsair does not leave all of this to the mobo systems. They use their own software tool, iCue, to do all the monitoring and control of the AIO system. To do that, the system includes a communication cable between the pump unit and a mobo USB2 header. iCue checks BOTH the pump and the rad fans for proper operation, and it does all the control of CPU internal temperature by varying the speed of the rad fans. That, too, depends on using the USB connection to communicate the fan speed control signals through the pump unit. So it is important to connect the system to the mobo as Corsair says, including all the cable connections, and including downloading and running the iCue software tool.
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