I recently added a second 780ti to my setup after getting a 1440p monitor. Previously my single 780ti would be at around 65-70 degrees under load. After adding a second video card the original one (top) would get temps of 75-80 degrees under load and the new one (bottom) would be at around 70.

I realize that in SLI config the top card will always run hotter but the temp jump concerns me. Even idle temp went up from like 30 degrees to 44. When playing higher end games like thief that keep both GPUs at 100% I have to manually bump fan speed to 70-75% to keep the top card at 80 degrees or less. Is this normal? Is there anything I can do to lower the temperature of the top card other than liquid cooling? 

Here is my current setup:
Cooler Master HAF X case with 200mm side and front fans for intake and 2x 200mm top fans and a 140mm rear fan for out.
i7-4770k
noctua NH-D14 cooler
asus hero vi motherboard
16gb of ddr3 1600 gskill ripjaw
256gb ssd
2x 1tb HDDs in raid1
EVGA GTX 780ti SC ACX in SLI
850 watt evga psu

Nothing is overclocked right now and all the wires inside the case are neat/hidden to maximize airflow. Fans are all running at max rpm. Any thoughts/ideas are welcome.

Does gaming/benching with the side panel off help with temps? If it does you need some better airflow within the case (with is a definite requirement with ACX coolers...) You could possible try to make the side fan exhaust instead of intake since ACX blows the hot air from the GPU out the side towards the side panel. Before I put my GPUs under water, both had ACX coolers and I didn't have any problems with temps. I installed extra fans to be sure air flow was more than adequate (positive pressure!!!). Also, you may have to give being quiet up and set up a more aggressive fan curve. Your new home is probably going to be 85-90% or more fan speed.

80C is ok but lower is always better.

ACX in SLI=NO NO.
 
Your temps will never be great. When your top card is doing nothing but choking on that hot air from the bottom card, theres not much you can do. 

I'll update some of my older fans and mess around with the fan config and maybe redo the thermal paste on the top card. With winter around the corner I guess I shouldn't worry too much about the temps especially since my apartment stays pretty chilly. By the time summer hits again next year I'll probably sell the 780's and get something from the upcoming 800 series instead. I'll just have to remember that ACX coolers don't do well in SLI. Should have done my research beforehand. 
 
Thank you everyone for quick replies. I really appreciate it.
 
 

Duck.... Watercooling will hush the fan noise... :-D