Z170M Pro4s VCore does not changes at all

Changing bios option [CPU offset voltage] to any value (0, 200, 300, etc) doesn't affect on vcore voltage.
I checked vcore value in bios after reboot and in windows i used cpu-z(1.75), HWMonitor (1.28).
Vcore value stay in 1.136, on an any offset from 0 to 500.
I can't OC my Pentium  G4400 CPU over 4.2ghz without increasing vcore

P.S.
I noticed when i reset BCLK to default (100), vcore increase to offset, and i can get any vcore 1.28, 1.3, etc. But only on default cpu clock, it's useless.

I use bios version 2.4

Thanks for the update