Hello,
I also contacted support directly, but do you have same issue, or did you?
Currently I have RB2011UiAS-2HnD-IN in living room and i have a big issue. When is traffic on Wi-Fi, for example 3.2 Mbps/1.6 Mbps and abou 340/280 p/s device is very noisy. It’s like „clapping“… CPU about 20%. Same issue at 6.15 and 6.16rc10. Device also make some IPsec tunnels. Sound is loud as for example printing on inkjet. If traffic is low, there isn’t any problém. Maybe sound is more like as ticking…
I have some RB2011UiAS-2HnD-IN and some RB2011UiAS-RM within 2011 models, but really till now i not have notice any strange sounds
Thanks for reply anyway. I have 5 RB2011UiAS there isn’t this problem. I have only problem on wireless model. Anyway i think, there maybe problem with wireless. I recorded video, where is the problem little hearable.
Current traffic 18 Mbps Tx / 5 Mbps Rx and about 2000 p/s
https://plus.google.com/photos/113765641000902876577/albums/6029757904570392145?authkey=CPzFnuHlsLWAPA
Ticket#2014062866000011
I heard such noise from of omnitik when it was sending huge amount of data via wifi. This fact doesn’t make any effect on real usage and on roof it can be good against pigeons. The sound explanation could be interesting anyway.
My wife will kill me 
Hello,
try to set lower tx power.