Microsoft announced on September 1 that, beginning in October 2026, Windows quality updates will start turning on memory integrity on more eligible devices. October is now here. If you own a Windows PC, you do not have to do anything, and for most machines nothing visible will happen. The few cases where something can go wrong are worth knowing before an update does it for you.
What Microsoft actually said
The text is in the Windows message center, which links to a post on the Windows IT Pro Blog. It says the rollout "will occur gradually, so the change might not reach all eligible devices at the same time." On some devices the change will also turn on virtualization-based security, or VBS, the layer memory integrity runs on.
Before enabling anything, Windows checks readiness "based on factors such as hardware capabilities, compatibility, performance considerations, Windows 11 system requirements, and recommended built-in protections." Microsoft does not publish the threshold, so nobody outside the company can say in advance whether a given PC passes. The notice says "more eligible Windows devices" and, in the text I read, does not list which Windows versions are included.
What memory integrity does
According to Microsoft's documentation, memory integrity runs the check on kernel-mode code inside an isolated virtual environment, so that only trusted drivers and kernel code are allowed to run. The goal is stronger protection against malware that tries to exploit the Windows kernel. It is also known as HVCI, short for hypervisor-protected code integrity.
Press coverage of the announcement says it already runs by default on clean Windows 11 installs and on Secured-core PCs, and that the October change targets the rest: PCs that were upgraded, or that shipped with it off. The Microsoft text I could open does not say that, so treat it as reported.
Who is not touched
Microsoft says "existing administrator and user choices and policies will remain in effect," and that devices where memory integrity was previously disabled "will not be automatically changed by this rollout." If you or your IT department turned it off, the update leaves it off. That is also the reason some people did turn it off: an old driver that would not load, or a game that ran worse.
Where it can cost you
Two warnings come straight from Microsoft's documentation. The first: some applications and drivers "may be incompatible with memory integrity," which can make devices or software malfunction and, in rare cases, cause a boot failure. The second is about speed. Memory integrity "works better" on Intel Kaby Lake and newer processors and AMD Zen 2 and newer ones; older processors emulate the missing features, "and will have a bigger impact on performance."
That is Microsoft's own statement and it gives no percentage. Tom's Hardware's headline says the feature reduces gaming performance on some systems; I could not open the article, so I have no numbers to give you and would not trust any figure that was not tied to a specific processor and game. The honest summary is that a recent CPU should see little change and an old one might see some, and the readiness check is meant to keep the worst cases out.
How to check yours
Microsoft's documentation says the setting lives in Windows Security, under Device security, then Core isolation details, then Memory integrity. If the toggle is on, you are covered. If it is off, Windows Security can show an incompatible-driver list, and the sensible step is updating or removing that driver rather than forcing the switch. If an update turns it on and your PC becomes unstable, Microsoft's recovery path is in the same document: update the driver through Device Manager, or recover through the Windows Recovery Environment.
If you are a gamer on an older machine, the cautious move is to check the toggle now, note whether it is on, and compare how your games run after the October update. If you manage PCs for others, the documentation describes controlling it through Group Policy, Intune and the registry; Microsoft's notice says those settings are respected.
This is a security change that arrives through the same monthly updates as everything else. For what Windows 11 version you are on and why it matters for support, see Windows 11 26H2; for another case where a September update broke something quietly, see the File History backup bug. Nothing in Microsoft's notice says when your PC in particular will be reached.
Last updated October 3, 2026