How do I manually set NB voltage? Is this the same as CPU FSB?

I have the voltages set to Auto for cpu and in cpu-z it says it is 1.32volts. Why is this higher than what others are getting in auto settings?

I flashed bios yesterday.... I have an E8400 on air and want 4.0ghz. I'm thinking I will set FSB to 1800 with a 9x multi. What voltages should I start with? I'm thinking since it says 1.32 in cpu-z it should be good for now.

Also I have sli enabled (expert) running linked with sync for memory. This should give me 900mhz. Do you think i'll need to loosen timings? Isnt the only other way to run 800mhz with an 1800mhz fsb to run unlinked and manually set speed? I'm new and need help.

memory is OCZ reaper pc6400 2X2 (that's why I need to know how to bump NB voltages) running at 1600fsb linked in sync mode with 4-4-4-15 timings.

Help me!!!