@Xdbeach
I have this MB, and the same mems (gskill 8800) and the same q9550. I can´t run OCCT stable @ 400FSB with Vcore=VID=1.250, PLL=1.5, NB=1.1, SB=1.1/1.5, and RAM 1:1/1.89v. All normal values. What are your values?

The high temps in NB are because bad mount sink. I've managed this tightening the screws sharply, especially the two just below the NB