using the latest version. Having 6 RX480 and 1 1070 cards.

I used to mine ETH with about 28 MH/s on each card then I switched to altcoins and getting until today a stable 200 MH/s with my 7 cards (28 per card).
Now switched back to ETH and getting only 17 MH/s on my RX480 and still 28 on my 1070 now.
All cards have 8 GB memory.

Any ideas what is wrong?

Thx
SJ