I got my new fan installed, the AK620, and the temperatures are a bit more stable than under the old inadequate cooler. However, it still hits 95c under an all core Cinebench R23 run and throttles to 5.1 to 5.2 GHz. Not great, I was hoping for it to be closer to the full 5.5 GHz even under a full load. Compiling a C++ program from source code doesn't heat the processor up nearly as bad now and temperatures stay well below 85c while holding at 5.3 GHz. That seems fine.
I'm hoping that as the CPU paste cures, Arctic Silver 5, temperatures will get even better. I may also have to play with fan curves, I don't mind the noise; I just want a (relatively) cool processor.
It looks like Arctic Silver 5 requires about 200 hours to fully cure and create a firm bond. Lovely.