My iMac is the 24'' with the 3.06 processor and I bought it on December 2008. A few months ago I installed Snow Leopard. Since then from time to time while my temperatures are normal without playing a game or something I notice that from 45C it reaches 70C all of a sudden. I monitor it through istat. If I reboot istat shows normal temperatures again! Can someone tell me why does this happen or if someone has experienced something similar?