Hey there. At the moment, I'm using 780 Ti in two-way SLI (not from EVGA, but both with proper custom air coolers), and I'm getting quite a lot of problems thanks to overheating. One card (the lower one) never hits above 70c, but the top one easily gets to 83-86c under load, with games like Evolve crashing after a few minutes unless I keep my case opened (temps are the same, but it seems to work more stable). Today I was trying to play Witcher 3, and even though I managed to set it up in a way that allows me a stable 60 FPS in 1440p (on a 2160p monitor), the game crashes on me, apparently due to overheating. If I keep my case closed, it crashes in under 2-3 minutes. If I open it, I can play for around 10 minutes, but then artifacts appear and it crashes yet again.
 
So, long story short, once I noticed the Hybrid version of 980, I decided to upgrade to it, putting one Hybrid on top (position of the most heated GPU), and one air cooled 980 at the bottom (since temps there are fine as is). Question is, which versions of 980 from EVGA would be compatible with Hybrid for SLI in terms of GPU dimensions? I've been looking into CLASSIFIED ACX 2.0, but it seems that it's somehow quite a bit larger if I were to believe the specs. Would be nice to have some official reply so that I don't buy two cards that I can't SLI due to size difference.
 
And a secondary question, seeing as how Hybrid would apparently be installed with it's fan replacing the back 120mm fan (case is Corsair 650d), how would I be able to SLI it with another Hybrid? Would that require a case with some sort of a side fan so that the second Hybrid's fan could be mounter there or something?

big, the classified is a MUCH larger card all around. The classified is meant for extreme cooling, like liquid nitrogen and dryice/acetone cooling. If you are spending the money of the hybrid, buy two of them. Don't buy one reference card and then one nonreference.

Stick with the same card for best compatibility. If you don't want two AIO, then buy the 980 Sc, which is the same exact card without the AIO on it, which guarantees compatibility.

Also, if you still have the 780ti's, try putting the current top card on the bottom. I did this with my 760's, and evened the temperatures out. You may be able to do the same also.

Scarlet-Tech
big, the classified is a MUCH larger card all around. The classified is meant for extreme cooling, like liquid nitrogen and dryice/acetone cooling. If you are spending the money of the hybrid, buy two of them. Don't buy one reference card and then one nonreference.

Stick with the same card for best compatibility. If you don't want two AIO, then buy the 980 Sc, which is the same exact card without the AIO on it, which guarantees compatibility.

Also, if you still have the 780ti's, try putting the current top card on the bottom. I did this with my 760's, and evened the temperatures out. You may be able to do the same also.

Thanks for your reply! The reason I wanted a nonreference air cooled GPU as the second one was because I find stock coolers quite bad at keeping the temps down, and was afraid that if I go that route, I'd have the same problem, but with the bottom GPU instead of the top one. At the moment both of my GPUs are nonreference with triple fans, and while they both do a superb cooling job when SLI is disabled, putting both under load produces too much heat for the upper card to handle, apparently, since heat obviously rises.
 
But I guess that if the top card is water cooled and super cool, the bottom one would show good temps even with a stock cooler. I actually didn't notice that 980 SC is the same design as a Hybrid, minus the AIO. Makes me wonder though...how come Superclocked edition is about 50 bucks cheaper on EVGA website than stock 980?
 
And I'd still like to see if any other model would fit, because buying one locally would be cheaper for me. For example, Superclocked ACX 2.0 shows identical dimensions on EVGA website, and I can get one of those at a shop right here (unlike Hybrid), so it would be preferable. I just want to be sure it'd fit.
 
About swapping current cards around, it was one of the first things I tried - didn't really help. So I either have two defective units, or there is simply too much heat. I upgraded cooling in the case to the best of my abilities and it helped, but apparently not enough. Besides, I have a faulty 4790k, which heats like hell on stock frequencies even when liquid cooled (45c idle, 70+ load), so that probably doesn't help either, since the top card is closer to it as well.
 

Scarlet-Tech
You are seeing a difference in the shroud itself.  The metal Titan cooler is expensive to manufacture, so EVGA created a plastic shroud that does the exact same thing, but reduces cost substantially.  This is the same for both cards when referring to the AIO and SC.  They will be using the same shroud, but one will have tubes coming out, so it would look like the same cards in the case.
 
If you do go with the SC, EVGA sells the AIO kit separate.  The AIO will NOT function with any ACX coolers.  It 100% requires the reference design, because it needs the blower motor to push air across the VRAM and VRM section.  
 
I still believe that 2 AIO's would be your best bet, because the FTW and the Classified are Both going to be custom PCB's, and although they have upgrades for overclocking, they are not going to provide you with any room if they don't overclock well (which happens occasionally) and they also cost $40 extra for items you legitimately will never use without keeping them extremely cold (negative temperature). Running 2 AIO's will allow you stock clock speeds that match, and you can guarantee both cards will remain cool, which removes an equation involving temperatures all together.. 
 
In the end, we can only make suggestions.  It is up to you with what you decide to do.  I am interested to hear back from you either way :-)

I think you may be misunderstanding my idea. I don't want the separate AIO kit they're selling, I want the pre-made Hybrid version that requires nothing more than plugging the GPU in and installing the fan. I want to add a air cooled matching card for SLI.
 
Running 2 AIO's just doesn't seem possible in my Corsair 650d since I only have room for one 120mm fan, and the only way to install water cooling on two cards in SLI in my case seems to be creating a custom loop that runs water through 2 GPUs and uses one fan. I just don't want the hassle.
 
So the idea is to buy that Hybrid, put it on top position, then put matching card at the bottom, SLI them, and OC as much as I can while keeping lower card temp low. Seeing as how I'm getting 68-70c under full load on my bottom GPU right now (which is factory OC'd and has custom cooling design), that is with a 85c hot GPU above it, I'm confident that with a cool Hybrid on top, I'll be able to push the bottom GPU quite a bit, since I'd be fine with it hitting 75-80c.

Scarlet-Tech
I have given my suggestions.  At this point, it is up to you.  Every time someone makes a suggestion you push back, so I am not repeating myself anymore on this subject. 
 
For the last time:  Card 1 is decided on........ GOT IT, you decided on the Hybrid straight from the store... got it got it got it.. Move past that and read the suggestions for card number 2 in the other posts above. All of the suggestions are above.  Any card in the inventory will fit in your case. i have made NO suggestions for changes to card 1. EVERYTHING above is for Card number 2. 
 
For the second 120mm fan, they make peripheral bay fan ports for 120mm fans. This was the one thing I forgot to address, so my apologies. 
  

I see, sorry, I must've misunderstood you there. Speaking of suggestions above, I can only see 980 SC being suggested, which is an option I acknowledged and looked into, but as I mentioned later, it would be cheaper to buy local, and the only option here is Superclocked ACX 2.0 (04G-P4-2983-KR), so my main question really is whether or not that one would fit in SLI. You mentioned that "any card in the inventory will fit", but I don't quite get what that means. EVGA inventory? Because above people mentioned that non-reference designed cards would NOT fit. 
 
Sorry if I'm being slow on this, I just never really had to deal with anything like it, always went for a single GPU, and this SLI setup I know have was a rather simple choice of buying 2 of the exact same cards without much thinking.
 
I appreciate the fan link, just looked into it, but it seems like 650d is a problem here, with such mounts requiring slight modding, while I want as little trouble as possible. With all the crap I had to go through in my last build, I want to think twice before upgrading to anything, and keep things as simple as possible, while being sure they work.

Scarlet-Tech
Do you still currently have your 780Ti's?  If so, did you try switching the top card and the bottom card to see if that corrected the temperatures a little?
 
The 650D is the exact case i have.  The cards fit in there with no issue, and by that I mean any GPU available when running in 2 way SLI.  There are cards that have 2.5 slot coolers, and even those will fit due to the clearance below the motherboard... I currently have 4 cards in one, as seen here:  
 
YES, they are watercooled, but that doesn't make a difference when running two way SLI, as your card will sit right between card 2 and 3 in my build. This shows the length and width of the classified cards as well. The only modification i had to make to get a reservoir in the upper bay was simply disconnecting the quick disconnects and then use screw to hold it in place.  You just lift the bottom of the latch, and gently pull out and it pops right off, exposing the mounting holes below.
 
I suggested the SC, because it has the option, with the reference design cooler, to upgrade to an AIO setup in the future IF you ever decide to. The ACX will work fine in this situation, but will not have an option for upgrading in the future. The classified will require a longer bridge, as it is over an inch wider and the stock bridge may not reach, unless it is the long flexible bridge, which will work.

Thanks for a fast reply. I do still currently have the 780 Ti's, and I did try switching them around, which didn't really change the temperature at all, sadly. Setup looks like this:

It's a bit dusty at the moment because of all the times I had to keep the case opened while playing - can't keep up cleaning it properly. (the temps however don't change after it's cleaned)
 
I understand that the case can take any GPU in 2-way SLI by dimensions, I was really only referring to there not being a spot available right away for a second 120mm fan if I were to get two Hybrids. Another reason I was earlier considering a larger case (along with another mobo) was to get extra slots and be able to have an empty slot between the cards, allowing for lower temps. In fact, I'd have simply done that and got this over with, but I also wanted to upgrade the GPUs for a while to get the HDMI 2.0 capabilities of the 900 series, along with a slight FPS bump (which is actually quite a huge increase in case of the Hybrid) for that extra 4K performance, since every few FPS matter there for now. I'll just go ahead and sell off my current cards as soon as I get the new ones.
 
And I didn't get that you meant SC being upgradable in the future at first, sorry about that, it's all clear now. It does seem tempting to have that option, but seeing as how ordering two GPUs from Amazon would add up to a price above monthly tax-free import in my country, I really don't want to go through the hassle of dealing with the customs and paying them quite a few bucks, so it looks like going ACX would be the better option for me. A last quick question regarding SLI bridge - compatibility tab on Hybrid page on EVGA website mentions this bridge as compatible: 100-4W-0042-LR EVGA Pro SLI Bridge V2 (4-Way), does that mean I'll have to use a large one like that? Because the thing is $40 on Amazon (which is pretty insane) along with a 1-2 month waiting time.