Thanks for posting. Apologies that your system is not performing as expected.
Your post doesn't indicate if you've run the system diagnostics yet. If you haven't, please run Dell SupportAssist, make a note of any error messages encountered and post back.
If there are no hardware issues, then this may be a software or driver issue.
Here is information from you may find helpful:
If you still require assistance and the system is under warranty, you may contact me privately. Be sure to include your personal information (name, address, telephone, email) and your computer's service tag number in your message. Thanks.
If there is no warranty, then you could contact our Out of Warranty team to get a quote for a paid service request.