Ok, so I just swapped mobos for the 3rd or 4th time.. Dual X5450 back online. I really didn't want to do this, but every other option would have involved downtime and monetary investment, both of which are currently out of the question.

And since this POS board has proven that it will die regardless of what settings I use, I'm now back at full speed. If it's gonna die anyway might as well do some damage while it lasts... Next RMA scheduled in 6 months