Microsoft Doesn't Want You To Know This Trick For Installing Windows 11 On An Old PC

Windows 11 wallpaper
Up until very recently, Microsoft detailed how you could go about installing Windows 11 on an older PC that does not meet the operating system's hardware requirements, and specifically the TPM 2.0 requirement. It recommended against going that route, but for those who were adventurous—and comfortable mucking around the Windows Registry—it made the steps available in a support document. That is no longer the case as Microsoft begins an earnest effort to get owners of older PCs to buy a new system.

Microsoft's urging comes as it gets ready to end free support for Windows 10. The soon-to-be legacy OS will reach the end of its lifecycle on October 14, 2025.

"After this date, Windows 10 PCs will no longer receive security or feature updates, and our focus is on helping customers stay protected by moving to modern new PCs running Windows 11. Whether the current PC needs a refresh, or it has security vulnerabilities that require the latest hardware-backed protection, now is the time to move forward with a new Windows 11 PC," Microsoft stated in a blog post.

The pitch appears to be working, as Windows 11 saw its market share surge last month, hitting a new high of 36.65% among all Windows PCs. That's up from 34.12% the month prior, and from 27.83% at the beginning of last year.

What Is The TPM Requirement?

TPM window in Windows 11.

TPM, or Trusted Platform Module, is a hardware-based security solution to protect users from malware and various cyberattacks. This can be a tiny microprocessor on the motherboard or embedded into the CPU itself (Intel has a great explainer on TPM).

When Microsoft released Windows 11, it made TPM version 2.0 one of the requirement to install the OS. This meant that some older PCs would not be able to upgrade from Windows 10 (or earlier). If you're unsure which version your PC supports, you can check by going to Settings > Privacy & Security > Windows Security > Device Security. Once there, click on Security processor details under the Security Processor heading to see which version you have.

Alternatively, you can press Windows Key + R, type tpm.msc, and hit OK. This will bring up the window you see in the image above.

How To Install Windows 11 On An Unsupported PC

As spotted by the folks at Neowin, Microsoft quietly removed instructions on how to install Windows 11 on an older PC that doesn't meet the TPM 2.0 requirement. However, a trip inside the Wayback Machine reveals what those instructions were. Before you venture forward, however, take note of Microsoft's warning.

"Microsoft recommends against installing Windows 11 on a device that does not meet the Windows 11 minimum system requirements. If you choose to install Windows 11 on a device that does not meet these requirements, and you acknowledge and understand the risks, you can create the following registry key values and bypass the check for TPM 2.0 (at least TPM 1.2 is required) and the CPU family and model," Microsoft explained.

You should also note that fiddling with the Registry can have dire consequences if you alter or nuke something that is essential. So, be careful. With that said, here are Microsoft's instructions..
  • Registry Key: HKEY_LOCAL_MACHINE\SYSTEM\Setup\MoSetup
  • Name: AllowUpgradesWithUnsupportedTPMOrCPU
  • Type: REG_DWORD
  • Value: 1
  • Note: Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
We'll also add that it's a good idea to backup your Registry before mucking around. To get into the Registry in the first place, type "regedit" in the Start menu. Then, choose File > Export to save a backup.