Hi @gendron thierry ,
based on the specs of Dell for the Optiplex 790 it looks like the CPU is an "Intel® 2nd Generation Core™ i7, i5 or i3 processor".
Source: https://i.dell.com/sites/csdocuments/Shared-Content_data-Sheets_Documents/en/us/optiplex-790-customer-brochure.pdf
A list with supported Intel CPUs you will find here: https://learn.microsoft.com/en-us/windows-hardware/design/minimum/supported/windows-11-supported-intel-processors
You can check the details of the CPU in Windows 10 yourself. There is no need to contact Dell support for this:
Open Settings
-> System
-> About
and you should see the details of the CPU in the Dell Optiplex 790.
https://www.windowscentral.com/how-check-your-computer-full-specifications-windows-10
Just check the CPU before starting any download or update on your computer.
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Regards
Andreas Baumgarten