I have 3.0ghz cpu on a esx host and 2.0ghz on other esx host. When I create a cluster, Is this cluster work as 2.0ghz speed?
I mean, does cluster lower the 3.0ghz to 2.0ghz on first esx for compatibility reason?
Each host will operate at the speed of the processor - you might get complaints about inconsistent performance as VM's are moved around the cluster, i.e. go fast of the 3Ghz host and then seem to go "slow" on the 2Ghz host. Depending on the workload and how sensitive people are, they might not even notice the different speeds.
Recommendation is to try running the same clock speed across the cluster but you don't have to.
If the CPU is a different generation (for the OS to notice), you should also enable EVC mode. I came across this recently adding a few new hosts to the VDI cluster. The golden image vm also had be be exposed / booted to both CPU's. Otherwise when a user logged into a session that booted on a 3GHz host they would be prompted to reboot the system. Nothing is seen if the vm booted on the older host and was migrated to a new host, only if it booted directly on that host.
I would test a VM booting on the new host and see if you get this error. You may end up rolling through and rebooting each VM on the new host.