What does CPU PLL voltage do?

What does CPU PLL voltage do?

This is the voltage used by the clock multiplier circuit inside the CPU

copied from rgone in another post

CPU Phase Locked Loop (PLL)
The default PLL voltage is 1.8 V, and Intel’s absolute maximum for this is 1.98 V, but you shouldn’t need to get anywhere near that. Intel’s new i7, i5, and i3 CPUs don’t require much of an increase in PLL, so you can probably get by increasing it to at most 1.9 V
Alot of Ivy Bridge actually like around 1.5 - 1.7 on the PLL voltage for improved clocking. Especially memory clocking.

this is from overclockers.co.uk

from masterslayer.com

CPU Phase Locked Loop (PLL)

This option can be used to stabilize the CPU at high BCLKs. Some people need to change this, and some don’t. You may need to start increasing this once you get to a BCLK of around 180 – 200.

The default PLL voltage is 1.8 V, and Intel’s absolute maximum for this is 1.98 V, but you shouldn’t need to get anywhere near that. Intel’s new i7, i5, and i3 CPUs don’t require much of an increase in PLL, so you can probably get by increasing it to at most 1.9 V.

weird some contradicting data google gives me

Thanks. I've gone from 1.5-1.8V on an e2200, and doesn't seem to be making any difference.