Other than RAM or your NIC not being seated properly or bad the only other two things I can think of are:

Go into Device Manager through Control Panel, do you see any yellow triangles?
And some type of system sound that you might have activated and forgot about.
No beeps when sound is muted. Still takes same amount of time to connect.
How did you mute the sound, did you go into Sounds and set the sound tab to no sounds or did you just shut off the speakers?

I did find some suggestions here: Dell Inspiron 560 Error Beeps