Guys, why all my cards(470,480,570) lost in hashrate about 10% ? I think it began slowing few month ago. There some problems with dag file or it's same as with old cards(7950) ? Is it possible to get prewious speeds?
Every new DAG hashrates go down until new driver is released.
Why new driver should fix it? AMD knows about this problem and has said something about this?
Because we are telling you the driver will fix it

Polaris has some issue with the DAG and AMD will fix it. I do not know if I should thanks them or not (due to difficulty increase).
AMD never thought that some many cards will be sued for mining, so it was not in their developement sheet to fix a DAG issue.
Now that lots of Youtubers and miners are reporting issue and going to buy Nvidia, they had to fix it.