Is it plugged into one of the fan headers on the mobo? How is it getting power?
I believe that it's plugged into the mobo and the PSU. I built it a few months before I noticed it. I am going to have to open it up and take a look. Unfortunately it's late at night here (7:43) and I have to wake up early for work tomorrow. I'm going to have to update this after work tomorrow.
I'm going to look at where things are connect take pictures and post the result on here.