Fan speed went from around 2500 to 1500.  That's pretty much the only change I saw. 

I may disconnect the blue pin when I setup the second antminer and have both fans run at full speed.  See if there's any change besides the obvious temp drop.

The 2nd fan is probably a waste of money but if you have a couple spare in case of primary fan failure then you may as well hook them up and put them to use.