Antminer S9 Highest Efficiency Operating Temperature

[Carsie]

Is there a specific temperature where the Antminer S9 works more efficiently?  If electricity cost and cooling was not a factor, would it run faster or produce more running at 5c rather than 30C?

[mikeywith]

According to specs on bitmain website for the S9k which I recall to be the same for S9/S9i and S9j ( I hope someone has archived those old models specs) it mentions this

(1-3) Min condition: 25℃, min J/TH, typical hashrate      

        Max condition: 40℃, max J/TH, max hashrate

In fact, the above Min and Max apply to all other miners including the new miners, the hotter the better in terms of hash rate.

Also in the table, it has 13.95th at 40c ambient temp and only 13.5th at 25c, which probably mean that the S9 hashes at slightly higher speed the hotter it the temperature is, however, it consumes more power and might reduce the lifespan of the miner's chips.