Here is a picture. There is a connector that comes up through the case to power the fans. There are 6 fans, each 23 dB(A). I believe it can be replaced by the user, since you do not have to open the main enclosure to replace them. The fans are kept off until the FPGA reaches a certain temperature (I believe 50C), and then they turn on (until the FPGA is below 30C), and I believe the fans turn off for phase noise measurements.
Let me know if you have more questions.