What kind of stress test did you run with the PC check up? Please provide us with the system model name and Bios version. 

its alienware 17 2014 model with 880m. Bios version A14. While doing the system stress test from dell pc check up application, temps going at 100c. Is it due to dust build up in heat sink? coz i havent cleaned up after buying , though its 2 months old. 

I opened the case and found fan blades with dust. 

Thank you for confirming this. Yes, please clean the fans as best as you can and use compressed air if you have any. After doing this, run the stress test again to see if there is any improvement. Also, try running a PSA/Diagnostic test.

This test can be accessed from the boot menu. Press the F12 key at the beginning when you turn on the system. This will take you to a boot menu, once you are in this menu select the PSA/Diagnostic option to begin the test. If you receive any errors during this test, please provide us with the error code and message. Can you please confirm when does the system turn off, is it randomly or when you are doing something specifically?  

Now its fine, it might be due to continuous usage of machine, and the room was also heated up in summer. Now temps r around 60 while gaming. It was shutting down when temps were going above 100c.

Thank you for confirming this. I am glad to hear its working properly now. It does make sense as to why it was going above 100c. Please let us know if you need further assistance. 

Sure