Drivers worked for me with some effort. Windows 10, 3 580 Gigabyte Aorus 8GB. Stock voltage was 1125mv.  

Out of the box, no luck with voltage control through Wattman. The Afterburner beta was able to bring the voltage down 96mv from stock, but it would quickly glitch and massively drop hashrate or hang.

Went in, flashed the bios with new voltages--875mv for each state, and I changed the top state from 1365mhz to 1125mhz. Raised memory speed to 2150mhz, stock memory timings.

Rebooted. Brought me down to 950mv.

I then went through Wattman again to change the memory controller voltage from 950mv to 875mv. Success! All three cards are again running at 1125/2150 and using 863mv. Temps and power consumption are now identical to what they were prior to the beta driver.

When I purchased the cards in May, each got around 26.7mh/s (~81mh/s total) under the above settings. That had dropped to ~24.5mh/s (~73mh/s total) prior to installing the beta drivers. Now, with the beta drivers, I'm back at 26.7mh/s (81mh/s total) over the last 24 hours.