If it is an XPS 17 there is a problem. Bad design. Even with a 100 percent working power adapter it cannot give enough juice for the top end cup and gpu. As a result, it throttles the cpu is you are doing gpu intensive stuff.
Dells fix is a motherboard swap that permantly slows the cpu.
This is their top end laptop. Not good.
What is XPS 17? How can I find out what model I have?