Interesting.  The problem hashing board now in my first S3 is working fine and very stable.  I just found there is a difference between my first well running S3 and the S3 that the problem board came out of, and that's is a different firmware on each.  I haven't found a way to determine while ssh'd in, e.g. opkg list | grep antMiner comes up a blank.  But, bruno033 pointed me to the firmware page and I see there the 0721.bin has a solid green light when running.  The first S3 from the mid-west has that.    When I saw that the S3 from Florida had a flashing green light when hashing I though I probably configured it differently than the first.  But it must mean the S3 I got from Florida has the 0711.bin firmware because the other later options are the 0811.bin and the 0826.bin, both of which will have the Advanced Frequency change option on the miner configuration page.  So, the questionable board is very stable at this point in the S3 having the 0721.bin firmware.  Time will tell if it remains at 441 overnight as the humidity rises, e.g. right now the rh is 30%.

soy