my setup

E6600 ES
Asus N650i
Kingmax 1GB DDR2 800
Galaxy 7900gs.
cooler master hyper tx
north bridge thermaltake extreme spirit II
south bridge no cooling.

i tried

vcore 1.5 (is it too high?)
9x400 = 3.6ghz cannot work.
9x387.5 = 3.487ghz cannot work.

now i'm on
9x380 = 3.42ghz.

see picture attached.

i tried 8x400 = 3.2ghz cannot work vcore 1.5
i tried 7x400 = 2.8ghz cannot work vcore 1.5
how should i set vcore?
memory voltage, what's the default?