So came across strange thing. i have only one rx480 in rig with few rx580s, everything was working ok up until maybe month ago.
rx480 started giving incorrect shares, a lot of them, before it would give few in a week. Now all of sudden, card would in give in 5 days 7 incorrect shares (normal more or less) and then would just start giving enormous amount of incorrect ones (every 3rd or 4th would be CORRECT one)

I tried to check logs, but nothing unusual in them.
Restarting rig helps, for 4-5 days then everything starts all over again.
Radeon software version 19.1.1
phoenix 4.1c

Did anybody have similar problem or know solution for it?

Thanks