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Why is Windows Module Installer churning my CPU?


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Was just surfing the web a bit this morning on my i3 and suddenly the fan started blowing hard. Thinking this was odd I checked my Task Manager and was surprised to see the Windows Module Installer taking up 25% of my CPU. I then checked updates to see what was being "installed" in the background. Turns out nothing.

So why is Windows Module Installer churning my CPU when nothing is being installed? Very odd. Went on for about 5 minutes then quit on its own. Checked in Services and Windows Installer was already set to "Manual" so it should not have been able to start on its own.

Disabled automatic SSD optimization just in case that was the culprit.

Will scan for viruses.

Any ideas?


I noticed that service is occupying CPU sometimes in the beginning... not lately, although I switched off auto-update, just to inform me when something is new and I decide when to download and install...


Well-Known Member
Yes, maybe that's it? It isn't installing anything, just checking? I'll disable auto install as well and see if it solves the problem.
I have exact the same issue since last firmware update on 8/19/14. I now have done an windows update cleaning and will use the troubleshooter again. Hopefully it helps.
@mitchellvii: Did you notice that it helped or is the issue still there?

Here it didn't help so i did a full factory reset today. All updates were installed correctly and without getting really hot.

Those things i realized:
1. Last time there were 44 updates after a factory reset. This time there were only 43.
2. Fan is much less likely to hear and I have the impression that the device is not so hot even under load.
3 I have several sleep study reports performed and in no one CPU was an activator as before
Two things i havent installed this time. I had installed a program before called "windows update notifier" and i didnt install firefox.
Still strange that a factory reset causes such a strong Change. Hope my SP3 will now work again good


Well-Known Member
I'd like to add that Windows 8.1 machines are some of the easiest I've owned in terms of performing "factory resets." Things just reconfigure themselves automagically, leaving pretty much just restoring files and installing desktop apps. I spend MUCH less time redoing my SP3 than I have other machines, making tests like this relatively easy.