I have faced the same problem with new blockchain drivers,
GPUs are stuck in P0, P1 or P2 states (300-600-900 MHZ core clock) after reconnection to pool.
This problem does not happen with old drivers.
So maybe claymore can fix it.
Simple setting -cclock in claymore config doesn't help, maybe writing high clocks in all states in BIOS can help, I have not checked it yet.