Around the time I started to undervolt the CPU of my Lenovo Yoga S740 using Intel XTU, the laptop shuts down after about 30 seconds when I close the lid. In the power management settings it says it should go into sleep mode when I close it. It's at -0.100V and it passed the stress test.
Undervolting is no longer allowed, as it is a security risk.
And, unless your processor is an X or K processor, XTU does not support it.
So the Intel support engineers can have more information about your system, Download, run, and save the results of this utility as a text file:
Then ATTACH the text file using the instructions under the reply window ( Drag and drop here or browse files to attach ).