To install Windows 11 on a computer that falls short of the specs
updated Sept 7, 2025

1)  You really, really need a solid state drive.  It doesn't have to be an M.2 drive. A SATA SSD will give you adequate speed.  Running Windows 11 on a spinning hard drive is super-slow and not recommended.
2)  Unless you have an M.2 drive, fast clock speed and at least 4 cores, you want at least 8 GB of RAM to get decent performance.
3)  Non-negotiable requirement:  The system must boot into UEFI (GPT) mode, not in Legacy (MBR) mode. The boot drive must be initialized GPT.  If you are trying to upgrade a computer running Windows 10 with an MBR drive, don't bother trying it - it won't work.
4)  Another non-negotiable requirement:  The system must use 64-bit architecture, not 32-bit architecture.
5)  Secure boot can be either enabled or disabled, despite the "requirement" that it be enabled
6)  TPM security can be either on or off, despite the "requirement" that it be enabled and be at least version 1.2
7)  Many processors and video cards that aren't officially supported will actually work.  Before attempting to upgrade a working Windows 10 system to Windows 11 with an unsupported processor and/or video card, make sure to back everything up, in case it really won't work.  I have had almost 100% success installing on Intel Core processors 6th generation and newer.  Occasionally, it will even work on a 5th generation Intel Core processor.  Tip:  Try booting to a Windows 11 flash drive.  If it won't boot, then it won't install.  Most of the time, if it will boot, then it will install successfully.  I have never run into a system that wouldn't boot due to a video card issue, but sometimes you get weird glitches due to an old video card driver.  
8)  After installing Windows 11 and booting to it, run all the Windows updates, including the optional updates, to fix any possible driver issues.

To bypass the "requirements," download and unzip the following zipfile containing the registry edit file.  This eliminates the hard-stop if the computer fails the checks for TPM, processor, video card, and/or secure boot status.

https://suekayton.com/software/Win11RegistryHacks.zip
If you are upgrading from Windows 10, before running the Windows 11 installer, import the unzipped registry file into your existing Windows 10 installation by typing the entire filename including the .reg extension.
If you are doing a clean install of Windows 11, after booting to a Windows 11 flash drive, hit Shift-F10 (or Shift-Fn-F10) to get a command prompt, click on empty space in the command prompt window, then import the unzipped registry file by typing the entire filename including the .reg extension.  Then close the command prompt window.
You can download a Windows 11 installer to create your own bootable Windows 11 flash drive from Microsoft - no login is needed.  
https://www.microsoft.com/en-us/software-download/windows11
Below is the link to purchase the $30 lifetime security support for Windows 10.  According to their web page, in order to use this, you must log into the computer using a Microsoft login, instead of using a local login.  I have not checked to see if this information is accurate.  If you are allergic to Microsoft logins, you could use the Microsoft login, run the updates, then switch back to a local login until it's time to download the next batch of updates.  
https://learn.microsoft.com/en-us/windows/whats-new/extended-security-updates