I suggest you stay away from stacked rigs like that.  If you were to monitor the cards on each row separately you will notice the cards on the bottom rack running the coolest with the cards on level 2, eating the eat from level 1, and level 3 eating the heat from levels 1 and 2.  If you set your cards to a maximum Temp.  They will start to throttle themselves as the temps increase.   If you want to maximize your hash rates.  Keep all racks on ground level.  Also don't be afraid to run your fans at 100%, unless the noise is an issue.