I am running ASUS Z270 Prime-A boards with Gigabyte 1050Ti Boost Clock 1506 cards. I don't think it is an ETH difficulty issue as my other rigs have the same configuration and I am not seeing the same issue. My power is set at 60watts, temp settings at 60, my fan setting 50, core OC is 0 and mem OC is 1450. I changed around power and mem settings, but no difference.
Could one of the modules be adjusting this to match one of the above variables? My cards never get hot enough for the fan to go above 50.
Autotemp could be lowering the powerlimit; but only after your fans go to max. If they don't go above 50% then that is unlikely. The current powerlimit is displayed by the autotemp readout, so you can verify if it has changed when this is the case.
If it has been; I would raise your temp target to 70.
Watchdog only restarts 1bash or the rig; it shouldn't make an OC changes.
What kind of risers are you using? Are you powering them direct with Pcie 6pin? If not this may be the problem.
Also you can probably get the same MH/s with the minimum powerlimit and -100 or -200 cc.