Constant Crashing During Gaming

Hardware Hub Build a PC
1

I just built my first gaming PC and after about 20 minutes or so of gaming my PC crashes, and then my bios cannot find my hard-drive. This is then solved by me changing what port my hard-drive is connected to on my motherboard. This has only happens with this game I have been playing for these last two nights (War Thunder on max/high) and when I had first installed Windows 8 and downloaded Google Chrome. The top of my case is a little warm as I play but right as I crash it gets significantly hotter but only right at the top, no where else. Someone please help me with this, it's getting really frustrating. 

Motherboard: Asus M5A99X EVO R2.0

CPU: AMD FX 8350

CPU Cooler: Coolmaster Hyper 212 EVO

GPU: Asus GTX 760

Power Supply: Corsair 600m

Case: Corsair 200r

Ram: Crucial Ballistix Sport 8GB Kit (4GBx2)

HDD: Western Digital Blue 1TB 

2

If it's crashing during gaming and when the GPU is heating up, might be a thermal problem. The 200r's airflow is  pretty restricted. I would check the temperature on the card when gaming or testing and if it's getting significantly hot, add a fan over the GPU or intake or just get a very well ventilated case.

3

Yep, check the thermals on the CPU and GPU, especially when under load.

Report back the temps.  Use something like OpenHardwareMonitor, Realtemp, GPU-Z, or Coretemp to view temperatures.