Before we start here is an article on how to check what level of EVC to use here.
One of the questions often asked, does vMotion works across newer CPUs in the same generation without an EVC cluster?
If you follow this KB, in the last paragraph:
Once the virtual machine is power cycled:
However, there are cases where vMotion will fail even the CPU is of the same generation due to an older version of VM hardware which has a more stringent check. As stated here, due to the destination host with a newer CPU with ISA extension not found on the source host.