Voltage diffence between core 2 duo and latest Pentium 4/D

Hello,

What is the diffence in voltage between core 2 duo and latest Pentium 4/D ?

I just want to understand if the difference is very important, or if a
manufacturer of a one year old motherboard (with chipset intek 945 or 955,
by example), can add support of a core 2 duo with acceptable overvoltage
(like overvoltage of user who overclock)