My best guess is this.
There should be ANOTHER voltage setting embedded in that ASUS BIOS. Look in any submenu having to do with "CPU Power Management" or "Digi+" or "VRM." Scour through the BIOS, but there could be a setting for "Extra Voltage for Turbo" or "Extra Turbo Voltage."
From my readings, the trick was to adjust the "Offset" voltage to a + value as close to zero as you can, while raising the "Extra" setting to get stability.
"Offset" may also affect idle stability. LLC can figure into getting that minimum voltage for stable idle.
Some folks have played with negative offset values, and it can work -- you just don't want it to cause a crash in the idle state, or when the system returns to idle after an otherwise stable load stress.
You also should have taken some monitor readings at stock and successively higher stable clocks. This would give you some guideline to compare in rechecking the BIOS monitors before you let it continue booting to Windows.