I know everyone has the problem of the top card being 8c-10c hotter than the bottom one. Mine was running at 82c on the top card and 72c on the bottom card, with my fan profile running at 86%. I made a 1/8" thick divider out of "clear" hard plastic material, that is the length of the card and the width extends out to my side fan (120mm) on my case. This separates the airflow for each card. Now my top card runs at 75c, and my bottom card around 73c after a 30 min run of Furmark, my fan profile is now around 77%. The divider sits about 3/16" over the top of the bottom card, this way the air can still flow over the top of the "bottom" card. I also took the covers off the empty PCIe slots on the back of my case. See attached image, It sure helped me and hopefully can help someone else.

Just stick in anything that separates the cards from each other, pretty well known fix

I like your fix, as it is nonconductive.  I had issues with my 760 ACX cards, with one running around 10c hotter, and it also clocked a little higher.. I switched them from top to bottom, and they both run at exactly the same temp now.. I didn't use a divider, BUT if I ever go back to ACX cards, I will remember this.  Thank you.
 
Also, please do post a better picture as well.  It would be nice for everyone to easily see.

I've added a picture of the divider to my original post. Obviously, everyone's divider is going to be different than mine. I'll see about getting a better picture of it in the case later tonight. It's not the greatest cosmetically, but it functions really well. I'm thinking about adding some EVGA badges on it after it's completed. I also have a mid-tower case, a CM storm in fact (4 fans), so making this for a small case was really easy.

Hmm, you just have it laying on top of the card? or do you have it tacked up somehow??