New Alienware 15 Gaming Laptop randomly shutting down when playing World of Warcraft

Hi,

I just got my new Alienware 15 Gaming Laptop today and started to play World of Warcraft. After gaming for around 15 minutes it shut down. Then I turned on and played for another 5 mins or so, it shut down again. Then I turned it on, added an external fan and tune down the graphics setting a bit, and it still shut down after just 2min. I literally just got this laptop. I wonder if somebody can help me to identify the problem.

Thanks