Cpu stuttering issue

Hello, guys. I have a Pavilion 15-cc140tx. While gaming with it, the frame rate drops from 60 to 10-12. Using Afterburner, it shows that the CPU frequency drops from 1600 MHz to 400 and voltage drops from 5.0+ to 2.8V.
If I run the game on battery power it is smooth. If I disable the Nvidia Graphics Card and run it with Intel GPU the game is smooth but the resolution and quality is down. It's been like this for 2 years or more. I couldn't find any solution. Nathan working at geek squad customer service number suggested to reinstall the windows on my laptop. After doing the same the issue was resolved and now it is working fine