try backing down the .77 to .75 yeah you may stay at 1600 but more stable show us this page
see all of mine are 85c due to under clock if you have a lot of 120 or 125c you are just a bit too much overclocked
As requested. I find it strange that I have such a variance in temps...or is that normal?

no the heat sinks are
_________ ____________
air flow >>>>> fan air flow >>>>
_________ ____________
So the air from the back two heat sinks gets pulled past the front two heat sinks thus two sets of numbers are always a bit higher.
You are close to perfect with your numbers that one with the 120 is setting 4.
you could set the startup volts to .685 for number 4 and drop the watts setting by 10 watts.
then check you asics again. if you get all at no more then 115 you are good to go.
I am running 7 in my garage so high clocks are a no go. I get about 1100gh an sp20 but I get to run 7 of them using around 4200 watts.
I have high power price of 10 cents in the winter allowing for the bonus heat.