Ah, you use headphones, no problem at all then
I'd expect the upper most card to get the warmest, then the middle one, with the lower being the coolest of the lot by a fair margin. It depends on spacing, where the cards vent the heat and air flow. With my 570's back when they were on air, I found that my side fan set to
extract made a huge difference vs. having it as intake. Now one of those 570's is in my media PC (different case, different flow) having the side fan on
intake is much better for temps.
Scoob.