I have worked on several laptops, 9 out of 10 dell laptops that are having problems are from heat related issues. Gaming would be pushing the limits on all of the hardware especially the graphics chip; and the cd rom drive would be spinning as well. My advice, put a fan underneath or behind the laptop, leave it off for a good hour to cool off, keep the fan on, turn the laptop on and immediately start up diablo or some other game. If the problem still persists then we can work from there, but there is a very good chance that if it is a dell the problem is heat related.