In Windows, disable Hibernation and Sleep. Also make sure Power Options is set to Balanced.
Reset the CMOS, or in the BIOS, load defaults. Then its just 8 steps to OC.

M.I.T. tab

1 Advanced Frequency Settings - Set X.M.P.

2----Advanced CPU Core Settings: AVX Offset - Set -x (I use -1 for 4.9 GHz)
3--------------------Turbo Ratio (x Core Active) - Set all at 50

--Advanced Voltage Settings

4----Advanced Power Settings: CPU Vcore Loadline Calibration - Set Normal

5----CPU Core Voltage Control: CPU Vcore - Set Normal

6-------------------------------Dynamic Vcore (DVID) - Set -0.110 V (Start with -0.030 V, then stress test in -30 mV intervals. CPUs typically step 100 MHz per 60 mV. Below -0.110 V, I have setting -0.060)

Chipset tab

7 VT-d - Set Disabled

8 Internal Graphics - Set Disabled

That's it, no manual voltages, no messing with LLC levels, etc. The only auto voltage that the Z390 Aorus Master sets high seems to be VCCSA at 1.3 V and VCCIO at 1.2V . (I have setting def voltage 1,050V and 0,950V)