I'm running an i7-2600k (no OC) on a z77-v pro mobo in an HAF 932 case. The cpu idle temps were high (35-42c) and after reseating/repasting did nothing I decided to replace the stock cooler I had. After installing my new Hyper 212 EVO however my idle temps are still in the same range. From what I've read those are high idle temps for the 2600k. Could something besides the heatsink be causing this?
Those might be considered a little high for idle but, nothing that will cause any harm. Heavier aftermarket HSF's are more effective with heavier CPU loading. I wouldn't expect too much from idle vs. idle comparisons. Don't empty your wallet trying to decrease idle temperatures.