Can you use Catalyst to cap the framerate/vsync in case the in-game options aren't working correctly? You should probably post a DXDIAG too for complete system info. Definitely seems like something that should be corrected.
Also, in general you should take a look at your heat dissipation in your system. While clearly the game is doing something that is making your GPU run at higher utilization than it probably should, it can't make it run at any more than 100%. You should be able to run your system at 100% CPU & GPU utilization indefinitely without overheating or you risk damage when you encounter something like this (probably a bug) or stress testing, etc.
