My farm is a mess with v12.0 - i'm moving back to v11.1 until claymore sorts out all the issues with crashing GPUs etc.
The strange part is that it seems v12.0 actually messed up my Fury cards somehow so now when I revert to 11.x they still crash. Could be some kind of odd coincidence but it seems unlikely.
You know, its funny you say that - i've just noticed the stability I had when I was originally using 11.1 has now gone after downgrading from 12.0 back to 11.1. This is strange.. However, the instability seems to be coming from only my 2xx/3xx cards.. RX4xx series cards seem to be running okay.