Microsoft blocks some PCs from Windows 11 24H2 — CPU must support SSE4.2 or the OS will not boot

Windows 11
(Image credit: Microsoft)

Windows 11 24H2 has received yet another hardware requirement for users with modded Windows 11 installs to watch out for. Bob Pony on X (Twitter) discovered that the SSE 4.2 instruction set is now required to run Windows 11 24H2, starting with build 26080. If the instruction is lacking, the OS won't boot.

If this sounds familiar to you, this new requirement is very similar to the POPCNT instruction requirement that we reported on several months ago. The only difference is that this new instruction set requires the actual SSE 4.2 instruction set. Previously only the POPCNT instruction inside of the SSE 4.2 instruction set was actually required.

This minute change won't make any difference to Windows 11 users today. All modern systems that support Windows 11 already have SSE 4.2. In fact, SSE4.2 has been around for nearly 20 years, and almost every processor has supported it for just as long. The only users potentially affected are tinkerers and enthusiasts who are trying to mod Windows 11 to run on incompatible hardware.

For one reason or another, Microsoft has decided to increase Windows 11's system requirements starting with version 24H2 which will debut later this year. These new requirements go beyond the original Windows 11 system requirements, consisting of Secure Boot, TPM support, and a Kaby Lake or newer CPU. POPCNT and the SSE 4.2 requirements are new and have been added specifically to 24H2 and will be applied to future iterations of Windows 11 going forward.

Bob Pony re-affirms that SSE4.2 specifically is required, this means that any older CPUs such as AMD's Barcelona chips that only go up to SSE4a won't work (through Windows 11 modding). Bob Pony has even made a Windows 11 24H2 tester that will verify if the latest Windows 11 24H2 builds with the new SSE 4.2 requirement works on your system. But again, this will only apply to an extremely niche subset of Windows 11 users who are customizing Windows 11 to run on incompatible hardware. Systems that can run Windows 11 today or come with Windows 11 will be able to run 24H2 without any problems.

Aaron Klotz
Contributing Writer

Aaron Klotz is a contributing writer for Tom’s Hardware, covering news related to computer hardware such as CPUs, and graphics cards.

  • Colif
    Depends if you running one of those systems if its good news or not.
    Reply
  • Notton
    AMD Barcelona? K10 from 2007-2012?
    People still use those and they have mobos that haven't failed?
    Reply
  • Dementoss
    Admin said:
    The good news is that this requirement only affects users who are trying to run Windows 11 on already unsupported hardware.
    Not exactly problem of the century then...
    Reply
  • edzieba
    These new requirements go beyond the original Windows 11 system requirements, consisting of Secure Boot, TPM support, and a Kaby Lake or newer CPU. POPCNT and the SSE 4.2 requirements are new and have been added specifically to 24H2 and will be applied to future iterations of Windows 11 going forward.
    Since "Secure Boot, TPM support, and a Kaby Lake or newer CPU" already means SSE 4.2 is available, these are not 'new' requirements, just a more explicit description of a subset of the existing requirements. If you met the requirements before, you meet the 'new' requirements by default.
    And since any CPU old enough to not feature SSE 4.2 would also be lacking support for TPMs (predating TPMs) or Secure Boot (predating UEFI), you would be well outside of the old requirements already, let alone the 'new' ones.
    Reply
  • hannibal
    Notton said:
    AMD Barcelona? K10 from 2007-2012?
    People still use those and they have mobos that haven't failed?

    People still use those. I did see one less than half year ago...
    Reply
  • logainofhades
    Microsoft doing its part to increase E-Waste.
    Reply
  • palladin9479
    edzieba said:
    Since "Secure Boot, TPM support, and a Kaby Lake or newer CPU" already means SSE 4.2 is available, these are not 'new' requirements, just a more explicit description of a subset of the existing requirements. If you met the requirements before, you meet the 'new' requirements by default.
    And since any CPU old enough to not feature SSE 4.2 would also be lacking support for TPMs (predating TPMs) or Secure Boot (predating UEFI), you would be well outside of the old requirements already, let alone the 'new' ones.

    It is "new" in the sense that it worked before and will not work now. This is likely just a result of compiling optimizations and MS simply not wanting to deal with supporting older code paths anymore.
    Reply
  • mitch074
    Notton said:
    AMD Barcelona? K10 from 2007-2012?
    People still use those and they have mobos that haven't failed?
    Actually, yes - an Athlon II X4 620 was a cheap quad core that could overclock like mad, and can still do stuff somewhat today. I retired mine as a media center last year, and it was still working, and even overclocking.
    Reply
  • TerryLaze
    logainofhades said:
    Microsoft doing its part to increase E-Waste.
    So anything that doesn't run (the newest) windows is e-waste?!
    Servers would like a word with you. (and apple and android and so on)
    Reply
  • coromonadalix
    kudos Msoft to piss more users and augment E-waste ... kudos
    Reply