If you have a faulty power supply (the mains cable on a laptop, the PSU in a desktop), then it can automatically start undervolting your CPU to preserve power. When undervolted, your CPU can function at only a fraction of its full power, hence the possibility of this manifesting as 100% CPU usage on Windows 10.

How do I lower my CPU usage Windows 10?

Why is it dangerous to have high CPU usage?

1. Guide to fix high CPU usage on Windows 10.
2. Method 1: Disable the Superfetch feature.
3. Method 2: Change your power plan to Balanced.
4. Method 3: Adjust Windows 10 for the best performance.
5. Method 4: Disable startup applications.
6. Method 5: Optimize your hard drives by using defragment.

How do I fix high CPU usage?

Let’s go over the steps on how to fix high CPU usage in Windows* 10.

1. Reboot. First step: save your work and restart your PC. …
2. End or Restart Processes. Open the Task Manager (CTRL+SHIFT+ESCAPE). …
3. Update Drivers. …
4. Scan for Malware. …
5. Power Options. …
6. Find Specific Guidance Online. …
7. Reinstalling Windows.