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Fans not running correct RPM

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I just put together a new build. I have the CORSAIR - iCUE H150i ELITE with 3 ML120 RGB ELITE Fans Elevate Your CPU Cooling. I also have 6 LL Series 120mm fans running on two Commander XL's. The issue I am having is that on one commander node I am running no more than 900RMPM, even when the extreme profile is selected. I then created a new profile and set the fans just to 1500 RPM to see what would happen. The 6 fans performed at 1500 but then the cooler dropped from 1600 to 1100 RPM. Before I upgraded cases, the 6 LL series worked great when extreme was selected. When I shut down my computer, before it turns off you can hear all the fans really ramp up. Any suggestions? If you were able to see the graph of my fans, it goes up and down, bounces from 820 to 940, back and forth. 

I have forced updated the software and nothing new happens.



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This is normal behavior, so no hardware defect. The issue is the presets on the Commander Core are using the coolant temperature (H150i Temp) as the control variable on that device. That is what radiator fans should use and is a good general case fan control variable as well. The Commander XT does not have a native coolant temp sensor since it’s not the AIO controller, so it substitutes cpu temp while using the same curve for coolant temperature. CPU temp is not a good fan control variable to begin with and it has no direct relationship to internal case temperature in these kinds of PCs. It’s also rather irritating because of the dynamic nature. 

Easy fix and you may want to do it for both controllers. Cooling and + to create a custom curve. Graph appears below. Go to the lower right corner with the shape tools. Those are your three presets, except now you can see and adjust the data points. Pick Quiet (or whichever), change the sensor to H150i Temp, then change all fans above to the new Custom 1 curve. Repeat for the other controller. The presets are improved from years past with their baseline temperature but you can raise or lower that to suit your environment. If it’s the middle of Summer and the coolant idles at 37C in a 32C room, nothing you can do will bring that down and blasting the fans won’t help. 

There is one small issue. As mentioned the Com XT controller does not have native access to the H150i temp data. This means CUE must be running to fetch the data from the other controller. If you spend a lot of time outside the CUE environment for whatever reason (Linux, testing, etc), you will want to use a temperature probe from the XT somewhere in the case to get an ambient temp reading and then make that the control variable. It will have a similar range to coolant temp but will work for that controller at all times, software running or not. 

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