First make sure your video card drivers are updated. Radeon autodetect can help you with this. Not just the integrated graphics processor in the CPU but the video card.
Scroll down a bit more to get to the CPU temp section. Scroll down further to get to the GPU temp section. Load a CPU stress test program like prime95 and see how high your temps get and if it crashes. Then do the same with a GPU testing program like Furmark which can tell you what your max temp itself. Give us the max CPU and GPU temps you can reach after a few mins.
If temps aren't the issue then try removing the graphics card and just use your integrated graphics. See if it crashes.