THAT IS WAAAAAYYYY HOT! First of all, get rid of your OC. That is most likely your culprit. Are you using stock cooling? A 400MHz OC isnt anything to turn your nose up at, and you would need far more than stock cooling to help cool that.
AS for your case; A case is a case is a case is a case. But airflow in the case, thats something you need to do work on to get it working right. Intake fans in the front, exhaust fans in the rear. Organize your cable clutter, as they are apt to greatly reducing your airflow. Good airflow is key. How much heatsink compound did you apply? What kind did you use? You may have applied too much, and it is impeding thermal transfer more than it is helping it.