In brief: The question of whether your ancient PC can somehow run Windows 11 is set to be answered definitively with a 'No' later this year. The Windows 11 24H2 update reportedly includes a requirement for a CPU instruction not found on processors older than 15 years - without it, the OS will not boot.
The hardware restrictions found on Windows 11 have been a controversial aspect of the OS since its arrival in October 2021. While there are workarounds in some instances, these requirements have slowed Windows 11's adoption in many businesses that still use vintage PCs.
According to a post on X from Bob Pony, Microsoft is making a CPU with the POPCNT (population count) instruction a requirement in Windows 11 24H2. Processors lacking this instruction will not boot the updated Windows 11.
So HUGE discovery found in Windows 11 Version 24H2, since build 25905.
– Bob Pony (@TheBobPony) February 11, 2024
A CPU with the instruction "POPCNT" IS NOW REQUIRED!
There are various system files requiring the POPCNT CPU instruction, from the Windows 11 kernel to the USB XHCI drivers.
Without POPCNT, it doesn't boot! pic.twitter.com/vCWYvzfu6k
POPCNT arrived in 2006/07 within AMD's Barcelona architecture, followed by Intel's first generation of Core i series chips, the Nehalem-based Core i7 CPUs, in 2008.
We've seen tinkerers running Windows 11 on pre-2008 PCs before, but that was more of a demonstration than for practical reasons. It appears that the arrival of the Windows 11 24H2 update, believed to land sometime in the fall, will prevent this sort of thing.
The vast majority of people are using a processor made sometime during the last 15 years, of course, so most PC users are unlikely to notice any changes.
The reasons behind Microsoft's decision to introduce the POPCNT requirement at this time remain unclear, though it could be another way of pushing more users onto its latest OS. Windows 11's worldwide share is still just 26.5% compared to Windows 10's 67.4%, according to Statcounter. The newer OS is faring better among Steam survey participants, though, with almost half of those taking part using Windows 11.
Earlier this month, Microsoft revived its full-screen, multi-slide Windows 11 upgrade nags for users of Windows 10, which reaches its end-of-life date in October 2025.
Microsoft recently confirmed that the Windows 11 24H2 update, which won't be called Windows 12, arrives this year. Like everything else in the tech industry, we can expect the update to have a heavy AI focus.