My miners were doing the same random beep as you describe, I setup the dchp server to fix an ip for each and the beeping stopped. Too many iDevices on the network seemed to cause too much conflict for temp. leases.
When you setup the fixed address, did you do it at your router by mac address, or on the S3?
EDIT: Never mind... I re-read what you wrote. Since you included the comment about setting up the DHCP server, you obviously didn't just put a static IP in the S3. Duh... sorry about the stupid question back at you.
Well, that didn't solve it on my side unfortunately. Still random beeps. That's going to get annoying quick...