You may not be aware but Dual Fan coolers vent heat into your case. This raises the ambient temperature thereby reducing cooling efficiency. A blower style cooler, although louder, vents 100% of the heat out of the case.
 
On the 7xxx series, the myth is that they vent only 50% of the heat into the case, and this is mostly true for other coolers with horizontal fins. With ACX and ACX 2, the fins are vertical as shown below on a 7xxx card. The rear exhaust is actually mostly being blocked by the outer fins!
 
If the 9XXX series is also using this cooling, then we have a problem.
 

 
Blocked vent below:
 

 
This means that ALL of the heat from the GPU is being dumped into the case. What makes matters worse is that the motherboard side of the heatsink is going to be mostly blocked by the motherboard. So, the only way for most of the air to escape is the opposite of the motherboard side, straight up to where the CPU heatsink is located, thereby even reducing the cooling of the CPU as well as the GPU.
 
Of course the problem is worse when an SLI system is involved.
 
This is going to cause severe cooling issues for people who have good to weak airflow in their cases. The only people not to be affected will be ones who have extremely good airflow with lots of fans and ports.
 
Yes, I know review sites have shown better cooling than blower heatsinks, but they are using OPEN test beds such as:
 

Without a case to surround the configuration, and the fins facing vertically laying on the horizontal test bed (compared to our vertical tower cases), of course, their tests are going to show better cooling. 
 
Unfortunately, this will not translate well to real world heat dissipation performance.
 
In summary, I propose that the best (and cheapest) cooling solution, although noisier, is a blower heatsink. Next, a horizontal heatsink solution where half the heat is vented outwards. Worst, is the ACX / ACX2 which are vertical heatsinks; which block a large portion of the output vent on the card and dump 100% of the heat right into the case. 
 
Remember: The hotter the GPU, the lower the boost frequency!
 
I would appreciate any counter opinions on the issue, and perhaps even some tests! 
 
I may be wrong, but knowledge is always good.
 
-- Zash
 
 
 

also, these coolers start to sag over time.  the rear of the card sags and then the fan will start to CHOP into the shroud 

I agree. And as what was said, it all depends on your case and airflow as well. With a full tower and great airflow, ACX in SLI can still give you better temps than blower in SLI. The spread between the two will be larger, yes, but still better max temps.

All Duel Fan GPUs have this issue for the most part, not only EVGA ACX / ACX 2.0 Cards.
For a Single Card they are Great and as long as you have one open Slot between each card they are fine for 2-Way SLI and with a good case even 3-Way SLI.
Your case needs to support this type cooler, so if you have a poor air flow case then you should get a GPU with the Standard Blower Cooler.
 
CAUTION! should be for all Duel Fan Coolers. Also most Non Reference Cards would not have a Water Block because most Water Block are made for Reference Card layouts
 
Note other Coolers:


 
 

Great info.  Which of the non-ref 970's use blower type fans?

I'm planning on an SLI 980 setup, should I got with 2x Blower, 2x ACX 2.0 or 1x Blower and 1x ACX 2.0 ???

geeklogik
I'm planning on an SLI 980 setup, should I got with 2x Blower, 2x ACX 2.0 or 1x Blower and 1x ACX 2.0 ???

2x Blower, why so that that later if you want to go over to a water blocks you will not have all the issues that users are having now looking for Water Block.
You should also try to have one open slot between each card for better air flow but you do not need it as bad as the Non Blower Coolers.
 
You should not mix models for SLI, the Clocks are not the same for the most part. You will need to compare the specs of each card and they should match for best results and compatibly.

I understand everything, but it's good because we have options.
If Radeon owners with Sapphire non reference cards not complain and their cards blow 85C in case non stop than Maxwell and Kepler owners are in much better position.
We have 3 option:
1. Turbine + AIO Exhaust = + Cold Case and fans almost don't need. - Loud and Less Space for OC.
2. ACX Cooler usually with heavy overclocked models = + More space for OC, More Silent, - More heat in Case (all of them blow air inside of case, where that's less important)
2. Watercooling = + Best for OC, + Best Ambient Temps, - High Price
 
We can choose and no one can't tell as during Fermi generation EVGA no dual cooler cards, because they had best system and cards came with very high clock. I would love, but they measure temps on ambient temps on bench table in room, not in restrictive space, everybody.
And ACX is very good in such condition. Best option is watercooling and I would love to more manufacturer produce more models of nice and simple Universal GPU Block for non reference cards because that can reduce price and people can keep same system for 3-4 generations.
 
ONLY ONE THING IS IMPORTANT AND NVIDIA MUST TO FINISH THAT, TO MOVE SPACE ON 90C.
THEIR CARDS CAN'T DROP CLOCK BEFORE 90C. 83C IS BAD SOLUTION.

sherpa25
Great info.  Which of the non-ref 970's use blower type fans?

EVGA GeForce GTX 970 Superclocked Part Number: 04G-P4-1972-KR $350
EVGA GeForce GTX 970 Part Number: 04G-P4-1970-KR $330
 
I would say on this Blower type 98% would blow out the rear of the case.


 

 
 
Maybe the GTX 970Ti or the GTX 970Ti Classified model (*If EVGA makes them) will come with this Blower:

Or USE an In Win S-Frame or D-Frame

Yah, when you use that photo it isn't too pretty...
How about this one:
 

wonder why the ftw has vertical fins? is the cooler more robust then the ones with horizontal, such as the sc?

godgxjs

mack-attack
wonder why the ftw has vertical fins? is the cooler more robust then the ones with horizontal, such as the sc?

wondering the same thing

Its all about airflow, when the fins are vertical then can exhaust more air from the fin stack, when they are horizontal less air can be exhausted therefore reducing cooling performance

The rad for my CPU is cooled by an intake fan on the back of my tower. Therefore ACX is a better option, as a vent fan would just blow hot air out the back only for it to be sucked back in by my rad fans.
 
It's not as cut and dry as "dumping air in the case is bad", guys.

I don't know if I should be waiting for the 970 FTW with 2.0. I've been reading around elsewhere (beside all the noise issue threads on this site), and see more reason to be scared. I'm definitely going to wait until one of you get it and give a review. There's a thread on anandtech showing some weird manufacturing on the 970 with 2.0. The smaller heatsink isn't covered. There are other pics from other reviews as well. Hoping to hear from reps about all these issues because I love my EVGA products. But for once I'm not rushing on it.