Well any mining has to take into consideration initial cost and running cost.
Bitmain hopes you are stupid and don't consider both. Fact.
So yes if you factor both in and find that one setup comes up with a better result, then indeed that makes sense.
There's of course the issue of miner lifetime - so you'd have to read around about the average reliability of an S7 vs an S9.
It would seem that 10% failure rate is somewhere in the ball park of what to expect on a typical miner - but YMMV.
Also of course don't forget that difficulty increases
That really doesn't factor much into what you are comparing, but often people look at the long term and don't factor in difficulty changes at all.
Bitmain hopes you are stupid and don't consider both. Fact.
So yes if you factor both in and find that one setup comes up with a better result, then indeed that makes sense.
There's of course the issue of miner lifetime - so you'd have to read around about the average reliability of an S7 vs an S9.
It would seem that 10% failure rate is somewhere in the ball park of what to expect on a typical miner - but YMMV.
Also of course don't forget that difficulty increases
That really doesn't factor much into what you are comparing, but often people look at the long term and don't factor in difficulty changes at all.
If your power is cheap under 4 cents a kwatt the s-7 is the way to go.
If your power is 7-9 cents the s9 could be better.
The worst problem for the s9 is break downs. I have some spare parts on hand for my s9s' 2 controllers
a link for the s7 controller if you buy the s-7
https://bitmainwarranty.com/shop/products/us/s7-control-pcb/
a fan link for you
https://bitmainwarranty.com/shop/products/us/fan_s7/
