The big picture: Microsoft’s shiny new OS has had a mixed reception, not helped by the fact that users considering updating/trying out the OS on their relatively recent PCs were put off by a stringent list of system requirements, accompanied by vague messaging around compatibility and updates for unsupported PCs. This situation has led to some interesting experimentation around Windows 11 installation on older hardware, with an enthusiast getting the OS to run on a 15-year-old Intel Pentium 4 661.

We’ve previously detailed on how you can bypass Microsoft’s TPM and CPU requirements to get Windows 11 running on your unsupported PC. And while that may be running an incompatible chip from just a few years ago, it turns out Microsoft actually supports Intel’s single-core Pentium 4 chip that came out in early 2006.

As posted on Twitter by user @Carloss_SM1995, Windows 11 not only booted on their machine, whose specs are noted below, but also claims to have it updated with Patch Tuesday.

  • Intel Pentium 4 661 3.6 GHz
  • ASUS P5Q 4 GB DDR2 800
  • Nvidia GeForce GT 710
  • 120 GB SSD

Of course, unsupported PCs are getting Windows 11 updates, at least for now, but what’s interesting here is that Microsoft’s Windows 11 Compatibility Tool actually counts the single-core Pentium 4 chip as a supported model, despite Microsoft specifying at least a dual-core CPU in its minimum requirements list.

Although not an ideal experience, Windows 11 on a 15-year-old chip is still possible, and it could only be a matter of time until Microsoft updates its unsupported CPU list and the PC Health Check App in what's increasingly looking like an arbitrary limitation to get users buying new PCs. For reference, the tool regards the more recent (and capable) quad-core i5-4690K as an unsupported chip.

Nevertheless, for interested users having an old, retired PC catching dust somewhere, it might be useful to note that Carlos installed Windows 11 on his test machine with the USB-based Windows 10 PE installer in MBR/Legacy mode and that no EFI emulation was involved in the process.