High pitch noise & buzzing from motherboard or psu.

Recently I decided to upgrade from an amd opteron 932 to a i7 920.

These are my components

http://www.newegg.com/Product/Prod [...] 6813128374
GIGABYTE GA-EX58-UD4P
http://www.newegg.com/Product/Prod [...] 6811119160
COOLER MASTER HAF 932
http://www.newegg.com/Product/Prod [...] 6820227381
OCZ Platinum 6GB (3 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600
http://www.newegg.com/Product/Prod [...] 6819115202
Intel Core i7 920 Nehalem 2.66GHz
http://www.newegg.com/Product/Prod [...] 6835233029
XIGMATEK Dark Knight

Other things inside the case are three hard drives, two are 640g and one is a 150GB raptor along with an ATI 4850 vid card.

I decided to keep my older power supply since it's 600w and thought it would be enough to handle the upgrade.
Here is the link: http://www.newegg.com/Product/Prod [...] 6817151025
SeaSonic S12-600

Once I got things running (win7RC) all was well until I started to hear a high pitched buzz. I tried to see where it came from but it's hard to determine if it's the mother board or the PSU as many suggest.

Through testing I've managed to make it go away, what I did was turn off/modify various settings in the bios. Then I proceeded to turning them back on such as power settings and CPU settings.
The last thing that I didn't restore was the CPU auto voltage, when it was on auto the setting was at 1.2555V but I switched it to 1.2000 and I think that's what made the buzzing noise stop.

Now my question is what's the best way to resolve this?
Get a better power supply or is it the mother board? (do more testing?) Return the mobo?

Thanks

Misc: The buzzing is when the computer boots windows and it usually stays while using the OS. It doesn't do it while in a bios screen.
When I was using my amd 932 it never happened and the i7 is at stock speed as well.