I have a really weird problem here.

My rigs (2 with 4  RX 470 each) were working fine for 5 days. I stopped them for 10 minutes just for maintenance; was getting really hot in the room.
After i started them 1 GPU in each rig shows a 80% drop in hashrate.

What just happened?

In essence 2 RX 470 dropped from 24 to 4.2 MH/s.

Anyone has encountered same issue? Also after 5 hours of operations, they freeze.

many thanx in advance for any tip

Forgot to add that it is only with ETH that i have this issue. When i use Claymore for zcash, all cards working fine