What your system and drivers?
Don't forget about this:
Please note that the usage of 4 GB AMD cards on Windows 7 is problematic, because the blockchain driver from 2017 doesn't seem to work properly with big DAGs, and the newer drivers do not support turning on the compute mode. There are some possible workarounds with patched/hacked drivers but we haven't tested them and can't tell you how to do it.
So, if you have Windows 7, forget about mining on 4Gb cards.
It says...Good drivers. These are versions from 18.12.1.1 to 19.7.5 (inclusive), and from 19.12.2 to 20.4.2 (inclusive). These will allow you to mine until DAG epoch 372-373 and won't need restart of PhoenixMiner on each DAG epoch change.
Some of my rigs still work no problem and some of them doesn't