A lot of skewed info here. The Fx line ups throttle is nowhere near 65 degrees. It's the APM, AMD's power management crap that cuts voltage to the CPU and causes massive performance loss. Disable this to prevent any throttling. I've learned this doing extensive testing using Physics benchmarks. You can bring these chips up to 75 degrees without issues.
Your issue looks like the result of bad contact. Either you are not screwing down your heatsink in a "Star pattern", or you have not put your thermal paste on properly. Put a pea sized amount on your CPU and use a razor blade to spread it, not your fingers.