That trying to prolong life of asics is bullshit...

That gear will be not usable after 6 to 12 months, so just get the max from it and don't care for their life.

I push them to the max and trying to mine as much is possible before next gen was released.
I have 2 sp20e and im lucky so far to not pay for electricity where they are located.
I sett one fan to 100% but second to 80% because there is very annoying fan resonance if both are set to 100% and that resonant noise can be heard behind wall.