Not sure what monitor software you're using, but make sure you're looking at the right temperature. I made the mistake when i was first overclocking. I was using CPUID HWmonitor and looking at the temperature marked CPU, but after some research, i found that it was displaying the socket temperature and not the actual CPU.
I started using the AMD overdrive tool as a double check for my temperatures when stress testing. I don't use the software for anything else, but the CPU status shows the thermal margin very clear for all your cores. This margin displays the difference between the max rated temperature for your cpu and what temp it's currently at.