I have some background in electronics and analyzing those intermittent failures that these miners have just got me a little confused, specially during a time that I checked control boards and data cables by disconnecting back and forth.
At times the miner was full throttle mining just to drop after few hours. That in electronics is called a "cold soldering". Although there are not visible cold solderings I discovered that the soldering material that is being used on this S17 have 2 problems.

First, high amount of lead and low proportion of tin, and of course zero silver in the soldering material. This can be observed under the microscope used to soldering circuit boards. All of the solderings showed a greyish mate color and no shinning finish.
 
Second, below normal temperature of the soldering material, also leaves traces, specially on the hashing board chips. Also analyzed under the microscope there are traces that look like an sponge along with tiny cracks surrounding the chip's area at the surface of the hashing board.