A couple of weeks ago, Microsoft rolled out Windows 10 update KB4100347. This was an Intel patch for Spectre Variant 2 and was supposed to protect more affected Windows builds. However, we later reported that this update was broken, sent to non-compatible machines and changing systems on others.
So, another Spectre Variant 2 mitigation has failed. Furthermore, KB4100347 is reported to be automatically disabling overclocking on Windows 10 PCs. Plenty of Redditors (1, 2, and 3) have posted proof this is happening. The problem affects numerous Intel-based PC, including those running Haswell-E and Broadwell-E CPUs.
It is worth noting the problem has only been observed in machines running the Windows 10 April 2018 Update (version 1803).
Microsoft has yet to comment on this problem, but the company has already fixed the issue. A patch for the patch, so to speak, was rolled out within KB4346084. That cumulative update was released with several other Spectre 2-related patches.
The problem here is Microsoft did not say KB4346084 included a fix for the KB4100347 problem.
As you would expect, uninstalling the KB4100347 update removes the problem of disabling overclocking. Despite numerous users observing the issue, no-one has been able to reach a concrete conclusion on why the update causes overclocking to turn off.
So, while this is a nuisance, in terms of failed Windows 10 cumulative updates, it's relatively tame. This is thanks to the easy fix. To remove (uninstall) KB4100347, simply head to the Settings app on Windows 10.
Once there, go to Update & Security > View update history > Uninstall updates. Search for KB4100347 and then click uninstall. Once the update is uninstalled, reboot your system to solve the overclocking problem.
Of course, installing the newer KB4346084 update would be better. This was you will fix the overclocking issue and still get the mitigation for Spectre Variant 2.