I've got a H80i too. I'm seeing 30c in Corsair Link, with my i7-4770k used at 5% (just watching a movie and surfing) and a room temp of 26c. The fans are set to about 900 rpm each. I don't think 50c is normal.
On the other hand, it's still nowhere near problem levels. Check you temperatures under load. If they're under 80c under load then you've got nothing to worry about.