Enhanced vMotion Compatibility (EVC) explained

During a DRS cluster creation, you can choose to enable VMware Enhanced vMotion Compatibility (EVC). This technology ensures vSphere vMotion compatibility for the different hosts in the cluster by creating the common CPU ID baseline for all the hosts within the cluster. All hosts will present the same CPU features to the VMs, even if their CPUs differ. Note that, however, EVC only works with different CPUs in the same family, for example with different AMD Operon families. Mixing AMD and Intel processors is not allowed. Also note that EVC is a vCenter Server cluster setting that is enabled at the cluster level, so it is not specific for DRS.

When enabled, this feature enables you to migrate VMs among CPUs that would otherwise be considered incompatible. It works by forcing hosts to expose a common set of CPU features (baselines) to VMs. These features are supported by every host in the cluster. New hosts that are added to the cluster will automatically be configured to the CPU baseline. Hosts that can’t be configured to the baseline are not permitted to join the cluster.