So I have my Corsair H100 cooler connected to the fan controller on the 600t Corsair White Case and everything was working perfectly for a few months. Then a couple days ago, I left the computer on for two days with fans on high (using the controller) and didnt notice a change. Then, just a few days ago, I turn the fan down and I see know difference. Eventually it went back down to the lowest speed, but now it is just randomly speeeding up and down after a random amount of time.
try connecting a different fan to your motherboard header and seeing what happens to that. if those fans work properly, it may very well be that you have dodgy fans on your H100. the replacement for those are Corsair SP120 fans (pretty much the best bang for buck fans)