Some Windows builds don't bother to check for a supported CPU

DJNelson said:

I just downloaded your WIM toolkit to see how well that works.

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Thanks for giving it a try. BTW, new version coming out tomorrow

ChatGPT:

What does the following mean?

Microsoft: "Important: You should verify that your device meets minimum system requirements before you choose to boot from media, because it will allow you to install Windows 11 if you have at least TPM 1.2 (instead of the minimum system requirement of TPM 2.0), and it will not verify that your processor is on the approved CPU list based on family and model of processor."

That message is basically Microsoft giving you a warning about a loophole that lets you install Windows 11 on unsupported hardware.

Here’s what it means in plain English:

The normal Windows 11 requirements​

Officially, Windows 11 requires:

• TPM 2.0 (Trusted Platform Module for security)
• A supported CPU (from Microsoft’s approved list)

If your device doesn’t meet these, the installer usually blocks you.

What “boot from media” changes​

If you install Windows 11 using a USB/DVD (bootable media) instead of upgrading normally:

• It may allow installation with only TPM 1.2 (older, less secure)
• It does NOT check whether your CPU is officially supported

In other words, it bypasses some compatibility checks

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Like others already said, this is the exception, not the rule. You can help AI by chatting with it and tell it this is not always the case. Besides, since you are using Rufus to create the USB flash drive it doesn't harm to bypass all compatibility checks so you can use it on unsupported computers as well. My main PC (2nd system specs) runs with UEFI disabled (Legacy BIOS mode installation), without TPM 2.0, without Secure Boot on an unsupported 3rd generation CPU. It cannot get more non-compliant, but it runs Windows 11 25H2 fine, I receive all updates normally, except upgrades to newer versions, and I have not noticed any drop in performance for being unsupported. So check your CPU with CPU-Z for SSE4.2 and then install Windows 11 without hesitation. If you install the OFFICIAL drivers (not rely only on Windows Update) and disable some useless startup applications, the performance is like running Windows 7 64-bit on the same hardware. Leaving all the visual settings enabled the performance is like running Windows 7 with Aero enabled. Turning off transparency, animations and fades on rather old computers the performance improves like disabling Aero on Windows 7 but with much better graphics than running Windows 7 with Aero disabled.

hsehestedt said:

We know this because it was officially published as a KB.

It was originally published under KB5005217. That section was removed at a later date from that article. So, the article still exists, just with that part removed.

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Hard to believe. Rogue developer?

More like rogue support specialist who got chewed out by the Windows product team. MS Professional Services owns the published KB articles, but they're not part of the Windows division.