Dell PowerEdge R630 machine check error when booting Proxmox 9

Actually encountered this problem a while ago, but forgot to write it up at the time

We have a Dell PowerEdge R630 that is running Proxmox 9. On update from kernel 6.14 to 6.17 the system started boot looping - the system would start to boot, and then early on when the kernel was booting it would stop and reset the machine. The iDRAC event logs showed that there were “Machine Check errors” occurring. Booting with the previous 6.14 kernel worked as normal.

The issue is described in Proxmox 9.1 known issues , and also in the associated forum thread. The fix is to enable in the BIOS:

It has also been suggested to enable X2APIC Mode.

After this the system should boot normally with kernels 6.17 and higher.