UPDATE: I improved support for systems with a lot of GPUs ( > 8 ) and slow CPU: less CPU load, EthMan works fine now. I will release new version within a few days, also some other improvements will be included.
Glad to here about the fix. I didn't know a Core i3 6100 is a slow CPU. With 13 RX 580's 8GB s on the ASRock H110 Pro BTC+ the load reported in Task Manager is ~35% I guess we need Core i7 to with 12+ GPU's in Windows.