Have you performed any recent hardware change?
Also, since when are you facing this issue?
It can be a heating issue. Please refer to the link mentioned below:
Also, please perform the diagnostics on the system.
Unplug the adapter and the battery. Press and hold power button for 10 seconds. Plugin the adapter and turn on the system. On the Dell logo tap F12 for One Time Boot Menu. Select Diagnostics or Utility Partition and hit enter.
Please keep me posted with the results.
Thanks & Regards