12-core single-CPU vs. 2 8-core CPUs

CompProbSolv used Ask the Experts™
I'm helping a client purchase a new server and have a question about single- vs. dual-CPU systems and the number of cores.

The immediate need for the server is not very strict.  It will be a Windows Server 2019 host with a DC and a File/Print server as two VMs.  I figure that an 8-core Xeon should be more than adequate.  Because the client may want to add VMs in the future, I'd like to have more than 8 cores.  I have two options to accomplish this with the Dell T440 we're considering.

The first is to use a Xeon 4116, which runs 12 cores at 2.1GHz and has 16M of cache.  The alternative is to have two Xeon 4110 CPUs, which have 8 cores each with 11M of cache each, and also run at 2.1GHz.  I expected the dual-CPU configuration to be significantly more expensive (both because of the additional hardware as well as having 16 cores total vs. 12 cores), but the difference is negligible in this context ($80).

I realize that 12 cores is likely overkill, but the client likes to buy more than he needs to ensure he can expand the use in the future.  This has served him well in the past.

I also realize that we could add a second CPU in the future, but that can turn into an expensive and disruptive upgrade he'd like to avoid.  The (list) cost now is about $525 to add the second CPU.  That's an acceptable expense to avoid a future upgrade.

My other concern about the 12-core CPU has to do with Windows Server licensing.  Though not likely, if we did want more cores in the future (adding a second 12-core CPU), that would require additional Windows Server core licenses, as I read the licensing rules.  The minimum is 16 cores, so the dual 8-core CPU arrangement fits in well with the license.

Is there an advantage to the single-CPU 12-core configuration over the dual-CPU 2x8-core configuration?  My inclination is to recommend the dual-CPU approach, but want some confirmation that I'm not missing something here.

Thanks to all in advance for useful advice!
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What does the client run?  Is it going to be cache intensive?  Then get he 12 core.  If it's not and they run things that can be parallelized, then get the dual 8 core.  You have more CPU processing power and you'll use a little more electricity running a 2nd CPU.

The 16 cores would maximize the Windows license, but you could always purchase more when you add the 2nd CPU or increase the total CPU core count by upgrading both 8 core CPUs.  Is he really going to upgrade those afterwards?  Has that been the case?  I see few clients actually upgrading a server before the standard 3 year replacement cycle these days, because they've been sized correctly before they need to replace it.  The only time this doesn't hold true is when the client is on a very fast expansion track and the company has a tremendous growth spurt.  Even then they're already at least partly in the cloud to take advantage of the on demand needs.
This client has been using the present server for much longer than 3 years, more likely 7 years or so.  By overbuying systems he's been able to get much longer life from the initial purchase and avoid the high cost of replacing a server.

At present, it will only be a Server 2019 host with 2 VMs: DC and file/print services.  There may be other VMs added in the future, so the added capacity is desirable.

I would agree that adding a second CPU at a later date is uncommon and is rather unlikely in this case.
kevinhsiehNetwork Engineer
I used to run up to 50 VMs on dual Xeon 5520 (quad core) processors. Anything more than 4 cores for current workload is overkill. It's hard to imagine running out of CPU on an 8 core system before the budget gets blown on RAM and storage. I am talking about multiple file servers, Exchange servers, web servers, database servers, and IT infrastructure servers for 800+ users.

The only think I am seeing is that is seems that some servers are requiring 2 CPUs before all of the PCIe slots are available.
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Distinguished Expert 2017

Adding to kevin's commonly, the memory dimms are dedicated to each processor.

Usually, you would need to purchase a paired set if cpus, you might not be able to simply buy another Xeon 4116 to convert the system into dual CPU. Even if you could, a second CPU will require additional memory to populate the dimms for the new CPU.

The confusion in licensing I think deals with licensing for user/devices when core/CPU licensing is discussed.

The OS license, 16core will be the one either 12 core ir 16.
900-1000 os license.
Yes.. I understand that RAM is dedicated to each processor and will purchase and install appropriately.

I've upgraded to dual CPUs before and have either purchased a matched set or have made sure that the second CPU is the same step as the first.  As mentioned, I'm not expecting to upgrade to a second CPU later.

No confusion on server licensing.
Distinguished Expert 2017

what was the growth of resource consumption for the old server.
Presumably the file server is outside the server age, the reason to renew.

Memory, might be a better investment if the two VMs are all that would run.
Thanks for the input!

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