Computer Crashes When Playing Intensive Video Games! Help!

Hello,

I have recently added a few parts to my computer. (GPU, 2nd HDD and RAM). Ever since i have upgraded playing games that are more graphically intensive every now and then while playing these games my computer would crash. This happened on Bioshock Infinite and Just Cause 2. My Specs are 

A8 3870k

Asrock A55m-vs

2 sticks of Patriot Ram 4gbs each

1 250gb hdd WB BLUE

1 1tb hdd WD BLUE

1 Sapphire 6670 1gb GDDR5

1 400w power supply (not 80 plus :( 

 After searching around i verified the game storage. Still didnt work. I think maybe my PSU isnt enough or maybe one of my parts are overheating.

Any response would help. Thanks! 

 

Yeah we'll if it isn't 80plus and only 400w it's probably the psu