I've been using the Noctua cooler for 5 years running my i7-920 at a ~30% overclock(2.67GHz > 3.8GHz). I can usually keep my idle CPU temp under 50C but in the summer, I have to drop my OC to 3.2GHz as the ambient temps in my house increase. I live near the beach which means no AC, just ceiling fans.
I installed an evo 212 on my brother's 4770K about 4 weeks ago. It is still at stock while it does some curing but the idle temp was about 38C on his with no OC. He also has a warmer ambient temperature house(77F-81F) like mine.