MB Fan #4 in Corsair Link?

I only have 3 chassis fans connected to my motherboard but I have a reading in corsair link for a 4th fan. Can someone explain what this is about? The fan I am referring to is in the list on the left side of the image.

I suspect MB Fan #2 is the fan header that your H100i v2 is connected to.

One way to test ... carefully use your hand to stop a fan.

The fan at the back of the computer is CHAFAN1 and the two fans at the front are CHAFAN2/3. I don't think my motherboard even has a CHAFAN4 header.

The pump and water cooler fans are all connected to the CPUFAN header.

I'll try to stop some fans to see if any of the readings change.

Fan#2 seems to be the strange one because I got a reaction on the readings from 1/3/4. I got a reading on #2 only a couple times when i was fiddling with the water cooling fans but not anymore.

So Fan #2 is the CPU Fan. The software doesn't really "know" what the fans are on the system bus ... that's something that you can label.

If you change your pump speed, that should change Fan #2 ... and that confirms that it's the CPU_FAN header. When connected, the pump will report about 1/2 of the pump speed as the fan RPM.

Thank you. I had my pump running in "Quiet" setting and switched it to "Performance" and watched the CPUFAN #2 reading increase as well. You're right that it is always roughly half the rpm of the cpu pump.

I've just relabeled it so I know it's something I don't necessarily need to monitor.