The Xbox360 is no quiet beast and I took a shot at quieting the thing down by buying a Talismoon Whisper Fan to replace the stock one. I know the Optical Drive is the source of a lot of noise too but not as dominant as the fans. Prior to installing the new fan I did a measurement with my iPhone and the "AudioTools" app by Studio Six Digital. I bought the SPL Pro Sound Level Meter app and did a measurement of a 13 minute Leq (An Leq is a time averaged measurement). I also measured the Octave band frequency spectrum and posted the before (xbox1) and after (xbox2), and HDD only (xbox3). The background noise in my condo is pretty quiet, about 35 dBA, so the measurement had a decent signal to noise ratio. I did the measurement at 2.5 ft. in front of the Xbox and I started the measurement immediately before turning on the Xbox. I then quietly played a game of FIFA 10. The stock fans registered: 59.8 dBA at 2.5 ft. (30 in.). I then installed the Talismoon fans and did the exact same test with FIFA 10 again for 13 minutes. The Talismoon fan registered: 56.1 dBA at 2.5 ft. Update: I then installed FIFA 10 to my HDD and played the game. It's results: 54.2 dBA at 2.5 ft. So the new fan was ~4 dB (3.7 dB) quieter, and with the HDD onlly it's 5.6 dB more quiet. That's actually pretty good! Now if only I had a bigger HDD (only have 20gb).