I have the same unit and you can hear it running. I can't say it's loud but it does run all the time. I don't use the GPS because I refuse to pay for a DVD when I have my cell phone and a Garmin that has free upgrades. I only use the unit for the cameras.
For what it's worth, that unit and the one in the bedroom run all the time. I have to push the buttons to eject the face plate to shut them off.
2006 42' Country Coach Magna VanGogh
525 CAT, Build # 6553 Pulling a 2011 Chevy Tahoe