Late last night, the CPU load while watching a DVD, caused the fan became obtrusive. I pulled the cover off, unplugged the fan, then leaving the cover off, I finished watching the movie. The only noise then being the dvd and hard drives chatting back and forth.
I think I have this fixed. I took one of
these small fans laid it on top of the cpu heat sink, and put two small sheet metal screws into the fins. The screws were chosen such that they just forced a pair of fins slightly apart as they were driven in.
I simply wired it in parallel with the existing controlled case fan.
Since the addition, I have not heard the fans run up during dvd playback.