@ColdSense... did you ever resolve the issue with the S5.  I too have this problem.  All chips look like they work when checking the GUI and only one temp readout seems to be above ambient.  If you look at the hashing boards you can tell which board is hashing because there is a red LED that will be illuminated on the board that is hashing.  The LED is close to the left power connector.

I have left my S5 running for a while checking-in on it from time to time and have discovered it is not always the same board that is not hashing. Sometimes it is the right board that is not hashing, sometimes the left.  So i know both boards work.... just not at the same time.

If i work out why.... I will post here. Any thoughts from others will be appreciated.