I have a zeon t5500 with r9 290 vapor x and cpu e5649. While playing high games like witcher 3 or gta 5 at 1080p or higher the pc shuts down completely after 5 or 10 mins of gameplay. I have a single cpu and 875 W stock supply. I observed the cpu temp of 50 C and gpu temp of 75 C when the pc shut down. What can be the issue. Please help...