Im also in the middle of researching and it seems that some BIOS versions implement an out of intel spec sleep mode or the makers are just too confident that SB can run at such low voltages for idle ( which is logical )
From what I've gathered this affects stock and overclocked systems, some guys can pass 200 runs of LinX with AVX and Prime Blend for endless hours but BSOD on idle/web browsing, they fixed this by either disabling all power saving or upping their offset voltage so that the idle voltage will never fall under 1.000v
In short just disable power saving OR try it w/o C3/C6.