Still cannot solve the issue.
I tried with nvOc 0018 and 0019.
To sum up:
I have MSI Z270 gaming plus (quite similar to MSI Z270-a PRO).
Previously 4 ZOTAC Mini 1060 6gb
Now added two EVGA 1060 6Gb
Celeron G3930

• Was mining well with 4 Zotac on nvOc0018 and OC
• I added two EVGA 1060 6Gb to the build, only 4 gpus detected always
• I enabled above 4G memory, 6 gpus detected, starts mining and the OS hangs after 5 min always
• I updated MB Bios and now it throws this error: https://imgur.com/a/QblT1 (No overclock)
• I tried with nvOc 0019 and it restarts after 10 minutes