Justapost, I printed Brother's BIOS template as well but for me that's a no go really.

Im priming now at 1.35Vcore, it just freezes or errors when running lower. No clue really how results could differ so much. 1.25V vs 1.35V is quite a significant change.

Ive Vnb at auto though, Vdimm at 2.12, all auto settings apart for TRFC, set those to 195. Auto settings results in 5-5-5-18, unganged DDR800. HT and Vht are stock as well.

I might have just bad luck with the stepping or I messed something up resulting in OC and Volt scaling.

Things I might check in future:
1) 2x DIMMs instead of 4x, maybe it affects stability
2) Testing how temperature and clocks affects each other
3) Try to get rid of freezing and find the weaker core, but the freezing seems to happen almost always.
4) Play with NB vs CPU ratio's both Volt and Mhz wise