If anyone knows if it's happening on all units or some only please let us know, I think this is a fantastic laptop, with a no go flaw.
I don't think anyone here can say whether it's happening on all units, but we have three reports in this thread with the Intel SL4 in the first week of release, and of course 34 pages worth of SL3 reports, so it seems as though it'd be safe to say it is by design.
I agree with you, it's a fantastic laptop, possibly the best Windows laptop of this sort yet. Unfortunately, if you're sensitive to that sound and work in a quiet environment - as I am and do - it may indeed be a no go.
Since we're years into this issue at this point I'd imagine it won't change any time soon, and also the majority of people must not notice it.
For me, it's a terrible design.