Well, I ended up doing some BIOS flashing last night and tried P30. With P26, I was at least able to boot into windows at 333x9. With P30, I couldn't even get that high.

I ended up trying P28 after that, and so far I am passing Prime @333x9. With either of these BIOS revisions, I seem to hit a FSB wall around 1400FSB. I tried an 8x and 6x multiplier, but the BIOS never gets past the initial CPU speed detection if I take the FSB any higher.

How accurate is the vCore measurement from CPU-Z or Speedfan for this board? If I set it to 1.3v in the BIOS, I end up with 1.25v-1.26v on idle in Windows and more like 1.23v on load.