That's actually quite probable. Mine has no ring to it and there isn't even much of the 40mm fan whine really. Same switch - ICX6450-24P.I got my icx6450-24p today, but my console cable won't be here until next week.. I take there is not really anything I can do until I get that?
A fan mod is definitely in the pipe for this thing,, I think the fans may actually failing as they have more of a high pitch ring than I was expecting.