The official AMD blockchain driver for windows 7 x64 does not work (miners crash).
The leaked driver from robinh00d works but nothing can undervolt my RX570's, only OverdriveNTool  works for a few seconds before reverting.

The solution that worked best is to use the leaked driver and the wattman from the official driver:

1.  Install the official amd driver with amd settings
2.  Without reboot install the leaked driver via device manager by going the "i have a disk" route (for all cards - one by one)
3.  If you have a modified bios, run atikmdag-patcher and reboot 
4.   Use wattman to apply your mem clock and volt settings
5. Open miner, everything will be ok except undervolt, now with miner running make a small change to wattman and reapply (for each card one by one)

The voltages appear to be sticking for as long as the miner is running , except for the main card that reverts occasionally.