just got x48 dk.... the big bro of this p35 dk. pushed my 8400 to 4.2g @ 1.31v. IIRC.... nb volt do play important roles. seems like nb n vcore must be balance.dunno y. n the d*mn EIST didnt function correctly. c1e yup. the solution? C1E + RMCLOCK.

EIST RESULT
1.31v vcore + EIST = 1.40v idle @ multi 9
1.31v vcore + C1E = 1.31v idle/load @ multi 6
1.31v vcore + C1E + RMCLOCK = 1.28v idle @multi 6 / 1.31v @ multi9

will test this mobo again later.