You needa get one of those PCI express extender cables + get air blowing on the cards. Mine are in a closed case with a fan blowing air onto the top of the cards, and one blowing air from inside the case towards the back of the case across the cards. There is a few inches between them, and they top out at 90 Celsius for a few hours on a hot day, core clock OC'd to 940. Each GPU is generally 70 to 75.
I also have some of those PCI slot coolers that suck air and blow it out of the case spaced under each card. The amount of HOT air blowing out of the back of this case is like 10 blow driers. I try to keep it pointed out the sliding glass door when I'm home. I'll have a good heater when winter comes along again though. It sucks 11 amps from the wall socket in full operation too.
This is the PCI slot cooler I'm talking about. http://amzn.to/jcJdZS