This is kind of an odd issue, as the documentation for Corsair Hydro coolers will tell you to plug the power into the CPU header on your motherboard. Having build a new machine recently, I see newer Asus board have a dedicated Pump header. I like these coolers as they work well and cost less than custom copper water blocks. The point of this thread however, is for older boards like the Asus Hero VII I had prior.
You want to disable the Q-fan options in your BIOS, as otherwise it will limit the pump output and not cool properly. For the Windows users, there is a Corsair Link application that will show you the pump rpm. In the case of a H80i cooler, this is typically running at 3200 rpm when set to the Performance preset.
Default will be around 1900 rpm with the balanced setting. So long as you are not running in an extremely hot room, that preset should be fine.
In your BIOS, check the following tree: Monitor | Fan Speed Monitoring | Fan Speed Control.
Set those to disabled and you should be good to go. Also under those settings, disabling the fan controls can prevent the CPU fan error on boot.
For item’s sake, I am using a H115i on this i7-7700k and was previously using an H80i with the i5-4690k. On the i5-4690k setup after a BIOS flash, the fan settings were reverted and I was feeling significant heat buildup in the top tube coming off the CPU back to the radiator. Temps were also quite high. Fixing the Qfan settings resolved the nasty temps on the rebuild.