Question: I have a new laptop which happily updated to Windows 11 and an older Lenovo stationary whose Xeon E3-1241 processor is not supported by Windows 11 so it has to happily keep running Windows 10 (except that Windows update nags me).

What is the criteria that my CPU fails so I cannot upgrade?

Answer: 
The requirements as given by Microsoft are at [Windows 11 specs, features, and computer requirements](https://www.microsoft.com/en-us/windows/windows-11-specifications).

For the CPU requirements they state:

> 
> 1 gigahertz (GHz) or faster with 2 or more cores on a [compatible 64-bit processor](http://aka.ms/CPUlist) or System on a Chip (SoC).
> 
> 
> 

Note that "compatible 64-bit processor" is a link.

It links to [Windows Processor Requirements](https://docs.microsoft.com/en-gb/windows-hardware/design/minimum/windows-processor-requirements) where you can find the supported processors for almost every recent edition of Windows.

From there you can find [Windows 11 Supported Processors.](https://docs.microsoft.com/en-gb/windows-hardware/design/minimum/supported/windows-11-supported-intel-processors) if your processor is not on that list then it is not supported.

Microsoft only support 8th generation or newer, and presumably their Xeon equivalents, on Windows 11.
If you want to know exactly what criteria is missing in your computer,
download [WhyNotWin11](https://www.whynotwin11.com/download/).

This utility analyzes each requirement for Windows 11 :

[![enter image description here](https://i.stack.imgur.com/exFU0.png)](https://i.stack.imgur.com/exFU0.png)