i have a little problem

why this message :
20:25:54:589   f50   watchdog - fminer threads hangs
20:25:54:589   f50   em hbt: 0, fm hbt: 121204,
20:25:54:591   f50   Miner thread hangs, need to restart miner!
20:25:55:638   f50   Restarting OK, exit...

it works normally , no drop hasrate , I do not understand.
Claymore 1 restarts once a day about my rig but also because undervoltage on my gpu

an idea?