I think with the S5+ monster and the S7 using the same 3 card chassis and controller with provision for 9 Hash boards, combined with the lack of an S6 and we have seen the way forward as being very high density modules, based on a single hash board design for single unit and 3 unit rack type units. Entirely geared towards Farms, with an S7+ and 14.58TH/S is the next logical step.
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The length of S7 is 301 mm
The length of S5+ is only 275 mm
The lenght of S5+ blade is 180 mm , height 127 mm at lower edge
The length and height of S7 blade are not known.