Thank you for responding !

NO, they are all bonestock ... Well, i think they are.
Funny thing is that 2 of them are identical MSI's yet 1 is running 1040mhz while the other at 1000Mhz .. In the radeon settings they are identical (apart from the core clock value).
Anyway to flash them to 100% factory default just to make sure ?
The other one btw is a 1025mhz Gigabyte windforce.

Any Claymore version you recommend ?  What about Radeon drivers ? (There are so many and usually the latest are not always the best for an older card like the 390.

Thank you for the Watchdog USB, didn't know such a device existed !  I am a Novice in mining so that probably explains.