kind of depends on what you mean by stopping.
- bluescreen will have a error code that indicates the reason for the system stopping
- if the system just freezes but still has graphical info on the screen, then the problem will generally be with the graphics software driver.
- if the system just goes to a black screen and reboots like you just turned on the system, the problem will be in the power system. Most of the time it will be caused by a power supply that is under powered or the extra power connection to the graphics card is not connected. ( enough power for 2D graphics but not enough for 3d graphics)
(could also be a related cooling issue, depends)
processor - AMD FX(tm) 6300 six core processor
8 gb ram