Now AMD driver limit max 8 GPU CF.
AMD works new driver max 12 GPU CF.

Sapphire RX 470 *8 : 22.5MH *8 = 180MH (for Ethereum)

Please watch: https://www.donanimhaber.com/anakart/haberleri/Bu-bilgisayarin-8-tane-ekran-karti-var-ASRock-H110-Pro-BTC.htm