Fps drop->Computer crash

So, for few weeks now I have experienced a problem while playing games:
I open the game, for few minutes it works fine and smooth, but then the fps drops to 8-13 and then my computer crashes after 1 minute of the lag. (usually my fps is from 45 to 150) I have experienced this game in all my games.

Here's my computer details:
Processor: Intel(R) Core(TM) i3-2130 CPU @ 3.40Hz 3.40 GHz
RAM: 4Gt
64-bit
 
Back