Just get a main breaker with a shunt. Apply some juice to the shunt (using any of the good multiple ways already mentioned), main breaker turns off, everything is off.
Turning the thing back on is never an "emergency", plus if you had to kill everything remotely you need to do a physical inspection before turning everything back on.
Yeah but turning on and off is a goal if you are avoiding the heat in a warm part of the world.
Also if you have cheap power from 8pm to 9am on and off is nice.
Got ya, people were asking about a way to get an emergency kill using servos to throw the breaker, I was trying to give them an instant and safer solution.
Cooling is a whole other ball of wax, but is much simpler. My rule is if you have enough cooling where just a few really hot days of summer get overly hot, just throttle the machines down on those days. If it is more than say a week or so you have to throttle down, then it is more cost effective to add more cooling. However, I run a lot of machines, so everyone needs to adjust that equation to their own unique situation. If you need to adjust machine usage to time of day usage write a script to kill mining during certain hours, get smart PDUs you can control remotely, get PSUs that need power_on sent externally, etc. Lots of solutions already posted to that problem.
