39C idle isn't brilliant tbh. 60+ load is ok, not super duper for a stock 3570K (I got that for 4.4GHz overclock).
If you just want to keep it the way it is, it's fine. If you want to overclock, check out the airflow (case temp versus room temp).
Basically, cooler performance is all about delta-temps. If you have a warm room, then you'll get warm temperatures. If the delta is too high (between CPU temps and internal case temp), then check the fitting, or paste. You should get something decent for the 612S.
If the case temperatures are too high compared to room temperature, then you have a airflow problem.