I would like to point out that the processor dropping doesn't have to mean the computer is throttling. It could simply be that the computer is bottlenecked somewhere and there is no need to be at full throttle. Just something to keep in mind while people are testing things out.
I still think this has to be a graphics issue because the computer can maintain a CPU load 100% with 2.2GHz+ as long as there is no significant graphics load.
I wonder if this graphics issue is why programs like MS Sudoku make the computer get so hot?
Edit: So I just did a test. I started Sudoku and the Intel power gadget. The CPU was doing nothing and down clocked to 800MHz. Not thermally clocked it just didn't have anything to do. That didn't stop the computer from getting very hot. Intel also indicated that I was pulling around 5.0W of power to just sit and do nothing with the CPU. The GT Frq0 was also reported at 0.6GHz, which I think is very strange considering something was drawing a lot of power.
According to a friend of mine that analyzed the code behind MS Sudoku , the cause of heat while playing this game is a library used by the game which was poor written. In another words, bad code.