I experienced the same problem with ridiculously high CPU useage after updating from Win8 to Win8.1. It turned out to be a known bug with a very simple workaround. I'm guessing that you're experiencing this same issue.
If you run Task Manager and go to the Performance tab, you'll probably see that the CPU utilization is really high (80-100%) for no apparent reason. Also, if you go to the Processes or Details tab, you'll notice multiple instances of a process called "sdclt.exe"
appearing & re-appearing every few seconds. These processes are causing your CPU to constantly run at near-capacity, and your fan is running at high speed in an attempt to keep it cool.
If this is what's happening on your system, here's the fix:
- Go to Task Scheduler
- Task Scheduler Library -> Microsoft -> Windows -> Windows Backup
- Disable the "ConfigNotification" task
- Restart your computer
I've experienced this same issue on 3 different systems so far. I've been able to fix all of them using the above method.
Please let me know if this fixes your noisy fan/high CPU utilization problem.
Amazing that Microsoft hasn't yet aknowledged this problem and issued a fix for it.
Same problem here with a loud fan after installing 8.1. I tried disabling the confignotification task and it seems to have helped a little but it's not running the same as it was before. I hope microsoft releases something soon.