it still still sounds like heat. first make sure all your heatsinks have good tight connections. Then make sure you have good airflow. I'd use two fans. One pushing air in the other pulling it out. here is what I'd do.. place the one pulling the air out right around your CPU and the one pushing it in at the other end. Good air flow is key. modern cpus are made to shut off if they get to hott so they don't damage the cache.