65 is too hot, though your readings may not be correct, depending on the placement and accuracy of the probe. Try re-seating the heat sink and fan. Clean them both off thoroughly, put on a thin layer of thermal paste, and put the heatsink on the cpu. Take it back off and see if there are any spots that did not make contact. Add a little more past to those locations, then reattach the heatsink and secure it. You aren't really able to add more case fans or anything, but don't keep the computer in a hot room, and be sure there is clear space around the entire box, so nothing is blocking the airflow.