I have a question: After i undervolt my pc by intel ETU, can i exit it out or i need to let it run in the background ?
Appreciate all your help
You should not undervolt your PC.
Also, unless you have an X or K processor, you should not be using XTU.
Please check Frequently Asked Questions about Intel® Extreme Tuning Utility, and you will find How do I completely uninstall Intel Extreme Tuning Utility? and other useful information.