Asus M4A77T Northbridge voltage ?????

Hi Everyone , im getting into overclocking but would like to know where my NB VOLTAGE is in my bios,i have an "VDDNB over voltage" setting and a "Chipset over voltage" are either of these the northbridge voltage??? but theres nothing which reads northbridge voltage specifically. ive been researching on the internet and looked in motherboard manual, which isnt very clear at all, but im still not sure so ill leave those on auto untill i know what im doing.the motherboard is an ASUS M4A77T.usb2 motherboard. its just that i read the adjusting the northbridge voltage can bring more stability to overclocks

My system is :

Xigmatek Midgard case, 2 intake fans and 3 exhaust fans
Asus M4a77t motherboard
16gb (4x4gb) Kingston hyperx Genisis Grey ddr3 1600mhz at 9, 9, 9, 27 @ 1.65v ( i got this much coz its future proofed and price of ram is so cheap at the mo,got the lot from overclockers for £58 using a promo code found in micro mart mag)
Amd phenom ii x4 965 Black Edition C3 revision 125 TPD 3.4 @ 4.1ghz ( 1.475v) using artic silver 4 and a Xigmatek Dark Knight heatsink/fan...idle = 30 C, load prime 95 = 53 C
Palit gts 450 sonic platinum
Corsair GS 600 power supply
300gb hard drive
500GB portable Hard drive
external DVD RW
Windows 7 Ultimate 64bit sp1

My Bios is upto date.

would be great if anyone could make this clear to me and let me know which setting is my northbridge voltage setting, thanks in advance.

without looking at your specific specs, I believe the the AM3 platform and 770chipsets usually run the NB stock @1.1v. When I overclocked my PII 945 I set my NB voltage @1.2v and seemed to stabilize my OC