Odd issue with Windows 10 and can't change clocks after adding 2nd card

I have an issue in Windows 10 Home 64bit, where the 15.12 Drivers do not allow overclocking, either via the miner application, Afterburner, etc. Even Radeon Settings will not open as it gives an error about cards not connected.
I ran DDU and made sure all drivers were uninstalled, updated to latest drivers, same issue.
Windows 7, no issue, but I seem to get better performance in Windows 10 by a small margin.
Is this due to Windows 10 or am I doing something wrong?
I ran a single 390 on Windows 10 with latest drivers hotfix, zero issues overclocked and stable, but the moment I added a second card, BSOD and had to recover to safe mode, roll back drivers, then it worked but no overclocking or even fan control.
And should I install AMD APP SDK v3.0 or similar?
Anything other than the primary video drivers? It's a mining only rig now.