There was a time when I managed a few clusters of MySQL servers provisioned on OVH bare-metal. [Yes, we know "they're the worst" at least used to be.] Everything was running well until we upgraded to their largest offerings. Turned out they had NUMA memory so had to retune the MySQL parameters. After sorting that out they all worked fine except one machine. Note that we already had a pretty good relationship so I'd already requested the exact same motherboards and BIOS on these machines. Somehow one machine always came up different. I couldn't trust OVH to set the CMOS the same so I carefully checked against one of the 'normal' machines. The cores reported differently and had different affinity characteristics. Never did find out why that was, perhaps a CPU microcode/stepping that I never investigated. Anyway I just worked around the issue (with a different tuning for this one machine) because asking for a replacement resulted in a similar situation.