Hi Claymore,
I believe the voltage issues with 9.8 and the beta driver, are specific to the RX580 cards, from what I've read the RX480s are just fine with the beta driver.
Not true, 480s here, voltage control doesn't work at all on the new driver.
on Afterburner, latest beta, try to set the voltage control in settings to thirdparty
Legend!
I hadn't checked that as the new AB had reset that option.
Thanks bro!
** EDIT **
Actually this half works.
One of my rigs (the one mentioned in my OP) works fine.
Just tried the same to another 6 x GPU rig (5 x RX470 4GB ref and 1 x RX480 8GB all Sapphires) and the voltage control remains locked.
Maybe it's an issue with the 470 Sapphires?
** Double EDIT **
This is nasty with the 470 refs.. Clay keeps crashing (unable to allocate DAG in the GPU memory) resulting in a total system freeze up.
May have to roll back.