I have a quirk with my H115i which happens only a few times a year.
I power the machine on and the light flashes red to indicate a problem - alas there is "no CPU fan detected".
Others who have experienced this issue seem to have high temps as well - my temps remain normal (about 35' while overclocked).
To fix the issue i just loosen the mounts, give the cooler a little wiggle, tighten up again and the system is fine for another few months.
Has anyone else had this or is it just me?