A random observation:
1. It seems that upon loss of internet connection, S5 sometimes latches on a funky state: fan is not spinning or spinning minimally, but temperature is rising.
2. We had intermittant comcast problems in the last few days, so i observed it on a few occasions.
3. I felt that air coming out was very hot, and upon restarting the miner by PSU, miner reported 0 hashing, but temperatures of above 80 degrees at the sensor, so i had to switch it off for 10-20 min, then it worked as it should.

I believe that someone described something similar before.
The solution should be in software, which should maintain fan speed at a certain (closer to high) speed until internet connection is reestablished.

The fact is that the S5 miner does not fully switch itself off on internet drop or, at least, does not maintain fan speed long enough to coool the machine after internet dropoff.