Welcome to the forums, Geletejo.
The first thought that comes to mind is the CPU is getting to hot, and its protecting itself by shutting down the computer. If you don't know already, the "AMD FX-8350 Black Edition" requires some serious cooling solutions especially in a case with inadequate airflow. You haven't indicated what case and cpu cooler you have. If your using the stock air cooler that came with the CPU, then this is likely the issue. Either way, I suggest removing the side panel from your case and setting an AC room fan (desk fan, floor fan, whatever you may have available with lots of air flow) beside the case about 12 inches away blowing cool air into the case. Now play your games, If the computer no longer shuts down mid-game you know the solution needed, a better CPU cooler. Hope this helps. 🙂