Changing voltage displayed in CoreTemp; What could be causing this?

[03storic]

So I recently installed Windows 8 as I was getting random restarts which I assumed was due to bad drivers on Windows 7 and now when using CoreTemp I can see that my voltage is sitting at 0.7173v and 799.94Mhz rather then the 3.5Ghz that it was before installing Windows 8 so would that be due to a bad PSU or connection? As I do not imagine that changing OS would change how the CPU is clocked.

Quick Edit: I also notice the voltage and clock speed change from time to time, sometimes it goes back to normal and other times it goes to about half power.

 

[makkara]

Note VID and Vcore is different thing. CPU will underclock it self when not all that processing power is needed to save electricity.

 

[03storic]

Note VID and Vcore is different thing. CPU will underclock it self when not all that processing power is needed to save electricity.

It is the VID that is changing, why did this not occur with Windows 7 and why has the computer stopped randomly restarting now that I have changed OS.