Fritz - for max oc (not 24/7) I am always using 900mv, 900mv on those settings. i found that 900mv on the pcie clock was needed for pcie of 119.
pcie 119 increases the storage subsystem performance when going for max pcmv scores.
900mv for the cpu clock might help cpu oc, not sure about that one though.

HPET on or off hasn't seemed to make any diff for me.