Rig total freeze, requires power reset

I have been mining between March and April successfully. No issues. At the end of April, my rig started to stop responding every ~6 hours. I have to reboot it with a power reset.

I started my rig again yesteday. A freeze happened today morning. I have looked at all logs

/var/log/miner/phoenixminer/phoenixminer.log
/var/log/kern.log
dmesg
/var/log/hive-agent.log
/var/log/syslog

I have found nothing. I have no idea what caused this freezes of the rig. It worked well for ~2 months in March-April.

I have tried already lowering the memory OC, did not change anything. My OC was stable for 2 month, so I don’t think it is linked to the OC.

I have no monitor attached to the rig ATM.