Ok, maybe that's all it is. I'm at 866 at the moment. I just learned I could tighten timings beyond spec, so I'm playing with tighter timings and lower voltages.
Spec is 2.3v and 5-5-5-15.
Currently at 2.1 and 4-5-4-15, 866 with cpu at 260x12, default vcore. This is since that screenshot, and stable as heck at the moment.
CL4 @ 1066 is a no boot though.