Feature requirement of this virtual machine exceed capabilities of this host's current EVC mode

Hi,

I recently upgraded to vCenter 6u1 and ESXi 6u1 from 5.1

I upgraded a VM to the HW v11 and the latest tools (9536)

After rebooting the VM, I have the following message in both the webclient and thick client "Feature requirement of this virtual machine exceed capabilities of this host's current EVC mode"

Does anyone know what this means?  It doesn't appear to be causing a problem.

The EVC mode of the cluster is "Ivy Bridge"

Thanks

Joe