Trying to get 4ghz stable with 955 P2. please help

[Shakeel]

Here is the rig

955 P2 BE
MSI 770 C45
OCZ 4GB DDR3 1600MHZ
AKASA FREEDOM TOWER CPU COOLER

HT LINK IS X12
CPU NB LINK IS X12

I can get 3.8 stable by just upping the multi but above that it bsods or restarts on occt

do i now have to up the fsb to get 4 ghz?

Can anybody advise me what to what voltages i need to have

there is

cpu vdd
cpu nb
nb voltage
cpu voltage

thanks

 

[Shakeel]

btw its a c3 stepping