I figured out why the temps were so high. I am running XBMC to display my media. Apparently because XBMC is not a multi-threaded application, the software causes the screen to refresh at 60 frames when in the media browsing menu. So if you have XBMC running, even if the screen is just sitting there while you're getting a beer, it's drawing the screen at 60 frames. I know, unbelievable, how could anyone let this happen.
Why does XBMC use x% CPU usage while sitting idle?
XBMC was originally written for the XBox game console, which is a single-threaded system (not a multi-tasking OS like Windows). As such, it was written in a game loop, rather than being event-driven. This means that the screen refreshes as fast as possible in order to "feel" responsive to the user. What this boils down to is that while sitting on the idle screen, XBMC is still repainting the screen at 60-90 frames per second (as can be seen by the FPS number if debug mode is enabled). This takes up a lot of processor power, because the "game" is still running, even though you may not be doing anything with it.
There are currently no intentions to change this, as it is a very low-level change of the entire XBMC platform. A few workarounds do exist though:
Enable the "blank" screensaver. This puts XBMC into a low FPS mode which uses much fewer resources.
Set an Idle timeout. In the PM3-HD skin, under Settings > System > Hardware there is the option to enable a "Shutdown function timer" and a "Shutdown function". The timer only counts down when media is not playing (it's not based on mouse movement like a typical screensaver). Setting the timer to something like 5 minutes, and the function to "Quit" will quit XBMC if no media has played for 5 minutes. It is also easy to use EventGhost or a similar application to register a remote button (or an Un-Idle event) to re-start XBMC.
Disable vertical blank sync in the System/Video Output directory. Alternatively, set vertical blank sync to "Enabled during video playback."
This issue is serious enough to have to seek out new media navigation and display software. The best part about XBMC is the user interface. Take that away, and I might as well use windows explorer to find the movies I want.
If anyone knows a fix, other than the workarounds from the wiki please help. I can't browse for a movie for more than 5 - 10 minutes without the processor heating up.
Also I should mention that the processor usage and temperature drop immensely during movie playback.