Hard to know what's happening exactly, there's a lot of reasons that could be the issue
Recently my rig that always works 24/7 started to crash, no new cards to me, and the problem was windows 10, with their updates messing with the mining
If you added a new card, I suggest you to uninstall and install drivers, using DDU:
https://www.guru3d.com/files-details/display-driver-uninstaller-download.htmlAnd them the latest driver from AMD, and use the latest miner available
But for real, if you don't use this rig as your PC, try some mining OS like HiveOS, simple mining etc