I have no problem setting 500 FSB & Ram 600MHz (5:6), took 2.17 vdimm to stabilize the ram with my TeamGroups haven't tested what my CellShocks need. I think this board is pretty much spot on with the vdimm, I measure within 0.01v from what software reads with a DMM.

You may need ~1.35 - 1.40 vNB to get it totally stable at 500FSB with the 5:6 divider, I was totally stable at 534 FSB 1:1 with 1.37 vNB and I could possibly have reduced it a little more but I didn't test.