Microsoft's war on old PCs appears to have intensified as the latest builds of Windows 11 will not boot if your CPU does not support the SSE4.2 instruction set.

The requirement was pointed out on X and follows reports in February that CPUs which did not support the POPCNT instruction could no longer run Windows 11.

At the time, The Reg initially wondered if the POPCNT problem was simply due to an engineer accidentally enabling some newer CPU instruction sets during compilation, but it now appears that the inclusion was deliberate.

To put Microsoft's move in context, the instruction set arrived in the first generation of the Core i5 and i7 processors, using the Nehalem architecture, more than 15 years ago. AMD's Barcelona architecture supported POPCNT a little earlier using a partial implementation dubbed SSE4a, but it appears that now only the fully SSE4.2 instruction set will do.

The Register asked Microsoft to confirm this, but was told by a spokesperson that the company didn't have anything further to share on the matter.

Microsoft's controversial Windows 11 hardware compatibility list excludes anything but relatively recent CPUs, meaning that users with hardware able to run the operating system without dodging the requirements will be unaffected.

However, users running elderly kit and with insufficient skill to deal with the hardware check might run into difficulty.

Then again, attempting to run something like Windows 11 using hardware from decades past would be pointless. Alternative operating systems are also available.

By extending the requirement to the whole of the SSE4.2 instruction set, Microsoft has tightened the screws a little more on users trying to persuade the latest version of Windows 11 to run on their systems.

While those users might be perfectly happy with their hardware, if they wish to run Windows 11, it appears to be time to move on to something that features the required instruction set and, ideally, is included in the Windows 11 hardware compatibility list.

We're sure Microsoft could recommend a hardware vendor or two. ®

https://www.theregister.com//2024/04/23/windows_11_cpu_requirements/