I just built a PC for use with Octane. In hindsight I should have used reference cards, but instead went with 1070 FTWs. The cards are great when separated, but I plan to use 3 or 4 eventually. I need to get these swapped out for 1070 FEs or a regular 1070. Other option is to go with a water cooling setup, and modify the FTWs I have. 
 
Looking for advice on what to do. Right now, I'm getting temps on one of the cards of 80-82 C. It's very close to throttling down, and I'm wondering what kind of a difference I'd see with stacked reference cards.

I have updated the BIOS on both of the 1070 FTWs I have, and have the optional thermal mods installed as well. Also have the aggressive fan curve applied. The reason I bought them in the first place was exactly for the reason you mentioned. In most cases they should provide better cooling than the blower (reference) design. When I have space between them, they stay cool. However, I now have one Hybrid 1070 FTW, and two 1070 FTWs together. I placed the Hybrid in the top slot nearest the CPU, thinking that it would stay cool enough to not matter where it was placed. Then the two 1070 FTWs are below it. The bottom 1070 FTW is doing well because it can exhaust air fine. The one in the middle however is getting hot. 
 
My ultimate goal is to have 4 GPUs in the case with temps that are well below that 83 C point in which they start to throttle down. My thinking is that if I'm planning on having 3-4 of these right next to each other, I should use the reference cards because they suck air in, and exhaust out the back. 
 
What would you suggest?