Did some more testing tonight:

BIOS settings:
-1.33 vcore
-+120mhz VTT
-1.64 vDIMM
-200x20 core

Windows:

-1.312 vcore no load, 1.360 load
-Core temps get up to 83°C according to RealTemp 3.00
-I can run Prime large FFTs for about 30 minutes before I get my first error.

Not sure if I want to turn up vCore anymore. Would turning up VTT some more get me stable?