Microsoft Excel on Windows 2019 terminal server - unable to use all cores

Question

Microsoft Excel on Windows 2019 terminal server - unable to use all cores

Anonymous

Hello,
Excel on our terminal server is apparently using only 2 cores although 36 are available. Multiple users are using the terminal server simultaneously - meaning the RDS (remote desktop services) role is installed.
Operating system is Windows Server 2019 Standard. The users use Office365 E3 license and mostly excel with makros.

We tried setting the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\Common\IdealConcurrencyValueOverride to zero but that didn't help.
We also tried enabling the Application.MultiThreadedCalculation property in VBA (we did the opposite of what is described here - https://www.remkoweijnen.nl/blog/2012/06/08/excel-2010-multi-threaded-calculation/) but no luck either.

Any ideas or hints would be much appreciated :-)
Many thanks in advance!

Emily Hua-MSFT 27,741 Reputation points

2022-06-01T06:41:53.727+00:00

Hi @Anonymous
I am mainly responsible for general issues of the Office clients.
And I suggest you update Office to the latest version to have a check.

According to "Multithreaded recalculation in Excel", we know that if the machine has multiple processors or processor cores, the operating system takes responsibility for allocating the threads to the processors in the most efficient way.

If enabling the Application.MultiThreadedCalculation property in VBA does not work, I suggest wait for some suggestions from Windows and RDS as this behavior maybe be limited by the system environment.

Thanks for your understandings.
zlesko-agc 1 Reputation point

2022-06-02T12:51:26.243+00:00

@Emily Hua-MSFT Having the exact same problem here. I bought the server for big Excel models and was using Office 2016 VL on it, worked fine, saw all 36 cores and up to 64 depending on processor grouping. Upgraded to Office 2019 VL, still saw all cores. Upgraded to O365, now only sees 2 cores. Bought a test copy of Office 2021 Home & Business (not VL) and installed that, only sees 2 cores. Unsure if this was something that got broken between the 2019 and 2021 versions or something that behaves differently between VL and subscription? Either way need answers from MS as this is causing huge issues and we are not the first to be posting about this. Downgraded to 2019 and back to seeing all cores again so this is not something to do with the operating system, it's Office.
zlesko-agc 1 Reputation point

2022-06-02T13:42:19.173+00:00

Here's another thread where they were using O365 and it seems like an update changed this behavior with no answers given as to why. We aren't looking for VBA hacks, this needs a fix.

https://social.technet.microsoft.com/Forums/en-US/c40a5d55-838a-4e13-aeb0-b26d7efd6199/excel-not-registering-full-amount-of-available-coresprocessors-for-formula-calculation?forum=Office2016ITPro

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Emily Hua-MSFT 27,741 Reputation points

2022-06-01T06:41:53.727+00:00

Hi @Anonymous
I am mainly responsible for general issues of the Office clients.
And I suggest you update Office to the latest version to have a check.

According to "Multithreaded recalculation in Excel", we know that if the machine has multiple processors or processor cores, the operating system takes responsibility for allocating the threads to the processors in the most efficient way.

If enabling the Application.MultiThreadedCalculation property in VBA does not work, I suggest wait for some suggestions from Windows and RDS as this behavior maybe be limited by the system environment.

Thanks for your understandings.
zlesko-agc 1 Reputation point

2022-06-02T12:51:26.243+00:00

@Emily Hua-MSFT Having the exact same problem here. I bought the server for big Excel models and was using Office 2016 VL on it, worked fine, saw all 36 cores and up to 64 depending on processor grouping. Upgraded to Office 2019 VL, still saw all cores. Upgraded to O365, now only sees 2 cores. Bought a test copy of Office 2021 Home & Business (not VL) and installed that, only sees 2 cores. Unsure if this was something that got broken between the 2019 and 2021 versions or something that behaves differently between VL and subscription? Either way need answers from MS as this is causing huge issues and we are not the first to be posting about this. Downgraded to 2019 and back to seeing all cores again so this is not something to do with the operating system, it's Office.
zlesko-agc 1 Reputation point

2022-06-02T13:42:19.173+00:00

Here's another thread where they were using O365 and it seems like an update changed this behavior with no answers given as to why. We aren't looking for VBA hacks, this needs a fix.

https://social.technet.microsoft.com/Forums/en-US/c40a5d55-838a-4e13-aeb0-b26d7efd6199/excel-not-registering-full-amount-of-available-coresprocessors-for-formula-calculation?forum=Office2016ITPro

Answer 1

Hi all

The key you need is below

HKLM\SOFTWARE\Microsoft\Office\Common
Key = Reg DWord
Key Name = IdealConcurrencyValueOverride
Key Value = "Core Number"

I run the below as a start up script which utilises a standard windows variable %number_of_processors%. I need this as the VDI environment I manage has VMs spec'd differently in terms of CPU Cores

REG ADD HKLM\SOFTWARE\Microsoft\Office\Common /v IdealConcurrencyValueOverride /t REG_DWORD /d %number_of_processors% /f

Hope this helps

Graham

Answer 2

Anonymous

Hi @Graham Jessop ,

thank you very much for your answer!
Excel is now using more then 2 processors - Woohooo!
Unfortunately our VBA Makro doesn't :-(
Is there a configuration we have to set?

Thank you very much for your help!

Answer 3

Graham Jessop 76

Hi @Anonymous

Great news about Excel!

Sorry, I can't help with VBA ... My line of work doesn't stretch to macros thankfully

Good luck in finding a solution

Graham

Answer 4

G C 0

We have a Windows 2019 Server STD VM running on Vmware Esx 7.0.3 on Lenovo server equipped with AMD Epyc 7532 - 32 cores, the VM has 12 cores assigned and in the Task Manager are displayed correctly while in Excel 2021 LTSC only two are available.

I found a workaround, if i run Excel using Windows 8 compatibility mode all the cores are detected.

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Microsoft Excel on Windows 2019 terminal server - unable to use all cores

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