If you have an issue with your H100i or H80i READ THIS POST before RMA!
There are many people who have issues with their corsair cooler. I have had all these problems, and fixed them. Some of the issues include:
-Fans on max
-Link not detecting the device (Can't configure anything of your cooler)
-Wrong block LED colours
-Fan rattling noise (it is not the pump)
The solution to the first 3 problems is to update the firmware of your cooler. (Try changing the USB header first, it sometimes works for some cases)
It took me a long time to find this download on the corsair forums.
Use Corsair Link, go to Options > Devices > Update Firmware and choose your H100i/H80i. Select the H??i_V1.0.5.S19 file you downloaded, and click ok.
Reminder: you need the latest version of Corsair Link that has support for the H100i and H80i.
The rattling noise of the fans can be fixed by running the fans on motherboard headers or direct power from your PSU. Replacing the fans will allow you to still use the pwm control of the H-i cooler, without the noise. (That is what I did)
I hope this helps many people and their problems! If you have any questions just ask