Adding new server to VMWare HA Cluster

I need to add a server to our current VMWare 5.5 HA Cluster.   Our current ESX servers are all running CPUs with Westmere architectures and the EVC mode in VMWare is set to Westmere Generation.

Our datacenter is recommending new servers with Xeon e5-26xxv3 cpus with the Haswell Architecture.   I could purchase something different but then they refuse to help support them.  

I read the Faq from VMWare and it claims I should not see any or at least very little loss in performance by adding it to the existing cluster.

Will there be a performance hit?  Or would I be better off to try and convince them to purchase 2 new servers and start a second cluster?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Are you using VMware vMotion and/or DRS, because EVC is only applicable to vMotion and DRS, not VMware HA.

As for performance, yes and no, it depends if your VMs, will use the later features of Haswell Architecture...

because in using an EVC Mode of  Westmere Generation, effectively you are turning your newer processors into Westmere processors.

see here
qvfpsAuthor Commented:
It looks like the cluster is configured for HA and DRS with EVC set to "Westmere" Generation.
Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Okay, so see the link, there will be a performance hit, but only if you need the newer features.

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