Ant pointed me to SpeedFan in this stackoverflow question.
I downloaded SpeedFan and it reports that my CPU temperature peaks at about 73C which seems to be normal according to this chart (although the little flame icons in SpeedFan worry me).
However, is a CPU fan speed of 3590 RPM normal? The CPU fan reaches this speed after I e.g. open thunderbird, tweetdeck and a youtube video in firefox. At this speed the fan spins so vigorously that I can feel a light vibration in the table above the computer, and it makes a high pitch drone/whine like an airplane taking off. Is my fan broken or is this speed much too high for a CPU fan?
Here's a picture of the fan:
Best Answer
73 degrees is a little high if you ask me. The RPM of your fan is determined by a host of things but ~4000 is fine I tend to like slower fans that move more air because they are quieter. If the noise is bothering you buy a large fan/heatsink for $30-40 and replace it
EDIT: After seeing the pics... That looks like a stock CPU fan, I'd replace it with something quieter, it will bring the temp on your CPU down and be much quieter. When you pick something make sure it's going to fit. You don't have a whole lot of space between the CPU and the RAM