Voltage issues (E8400 & INFINITY DARK P965-S)

Hey guys, I tried searching the forums here to no avail so I thought I'd make
the thread. (If there is one, please close this and direct me to the right link).

I currently still own a DFI INFINITY DARK P965-S and have it flashed to the
newest BIOS (9-16-2008) for 45nm support. I now just bought the E8400
(details in signature) and got it all working thus far and have it overclocked to
3.81 ghz.

My issue is this however. During BIOS, the voltage reading for the cpu is
1.21V, while in windows, speedfan, and smartguardian currently read at 1.36 - .37.

Before I continue to overclock and possibly overvolt, which meter should I trust?

FYI: Right now, as it stands with the overclocked speed, its temps are:
Idle: 10-11C
Load (using orthos small FFT): 27-32C
All AIRCOOLED

Thanks guys! =)