Tested now few things:
Test Rig: 2 Cards
→ Changed Only mem clock. Works for now.
1060 Rig with 6 Cards:
→ Changed mem settings to same Value (1000)
Cant set fan speed → Phoenixminer reboot
The weirdest thing about it?
The error does not come because an overclocked card. Its coming because of an Stock Card with only Powerlimit (wich worked 3 Weeks long without an issue).
After changing the Settings of the other Cards its not working anymore → Now after an reboot an other card has the failure now its one of the oc cards.
I dont know whats wrong tbh. Running in circles.
Greatings.