I'm testing these new drivers..

So far no problems at all with 8x RX470 4GB .. rig has been runing 228MH's on ETH on blockchain drivers(23aug), it's running the very same hashrate on 17.10.2(23oct)

All you need to do is change workload type to compute for all GPU (individually, I know, it's pin in the a$$).. restart your rig afterwards and .. you're ready to go
For Overlocking use latest OverdriveNTool 0.2.0 .. everything works like a charm.. Rig is running 30+ hours now

In the evening I'm about to add 4 more cards to achieve 12 (also planing to test 13) and do the testing.. Just wanted to have confirmed that it's runing just fine with the same hashrate on 8 cards.. CONFIRMED !

AsRock H110 BTC Pro+, Windows 10 x64 1703 (no need to update to 1709!), 17.10.2 drivers, OverdriveNTool 0.2.0 with scripts..