There's room up top for 3x 140mm or 2x 200mm or 3x 120mm. Here's a pic of the side of the case and I've drawn rectangles to show where the 140mm fans sit in the top of the case. The two green boxes are where the fans sit over top of the main compartment, the red box is where the 3rd 140mm would be positioned over top of the 5.25" bay where there's no components except the front usb/audio connections and below that possibly an optical drive. There are no heat generating components there so to speak. The orange box shows the location/size of a full atx motherboard to give you an idea of how far forward of the motherboard/gpu/cpu the 2x 140mm fans are positioned.
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The only other fan mounts are the rear exhaust (140mm included, a good fan both quiet and moves a lot of air) with options for either 140mm or 120mm. The front fan mounts accommodate either 2x 120mm, 2x 140mm or 1x 200mm. The 200mm moves an ok amount of air, 2x 140's would move a bit more air up front. There's room to mound 2x 120's or 1x 140mm in the bottom but kind of a moot point if you use the psu cover and lower hdd cage since they block the bottom intakes and they're not really necessary. More or less for placing a radiator along the floor of the case in place of the hdd cage/psu cover.
There's also mounting for up to 2x 120mm fans mid chassis and they attach to the hdd cages. I think it's kind of like splitting the difference, it would be useful if leaving the hdd cages installed and filled with hard drives, the mid chassis 120mm fans would help pull the airflow through the drive cages to the rest of the components and past the hard drives installed there. If you don't have a ton of hdd's you won't need both cages installed. I opted to remove the center drive cage which removes any obstruction between the front intake fan and the gpu. The lower cage is still in place and holds my hdd, out of the way of everything.
Your temps won't be a whole lot different than mine. The 980ti sc+ runs 76c under furmark. My card is older, an xfx hd 7850 and it runs 74c under furmark. I'm not running an i7 but a 4690k oc'd to 4.6ghz. Even when gaming the only time I turn my fans up is during a hotter day. With just the stock 140mm rear, 200mm front and 2x 140mm top exhaust fans all turned down via a fan controller my cpu is only reaching around 32-33c at 20% load with an ambient room temp of 26c. Just trying to give you an idea of the environment my pc is running in and how it's handling heat with the fan setup I'm using. Just my opinion but I think the 2x 140's in the top is a bit overkill, but then I planned to turn them both down too in order to keep the system quiet. Low rpm's, more airflow moving with multiple larger fans means continuous airflow with little noise similar to using an oversized radiator. Rather than have a single 120mm fan whirring at full speed putting out a lot of noise to move the same volume of air.
So long as you won't be paying a shipping penalty or anything for multiple orders, my suggestion would be to start out with a couple of 140mm fans. Unless you're just looking to fill every fan slot in the case for looks or something, then you can determine if cooling is adequate. If so, then you've saved yourself the money of additional fans. Rather than buying a ton of fans and realizing it's way overkill.
In my situation, I opted for 140mm noctuas that ran $20 each. $40 worth of fans was plenty for my cooling. Had I just gone ahead and loaded my case full, I would have spent $100 in fans (3x 140 on the top, 2x 140 in the front) and seen little to no gain over what I currently have. A poorly ventilated case will impact cooling but it reaches a point where there are diminishing returns. You can only move so much ambient air through a case before it no longer provides significant cooling.
With all the fans turned down, assuming the front 200mm with a top cfm of 110 at full speed is only pushing 80 cfm (roughly 70% speed) and the additional exhaust fans turned down as well capable of moving 70 cfm out of the case (likely more, but for sake of low estimates) that's quite a bit of air. The dimensions of the enthoo pro, not including volume taken up by things like the components, is 2.441 cubic feet of air volume. Even factoring in airflow inefficiency and moving only 50cfm through the case, it's exchanging the case air 20x per minute or once every 3 seconds. Any air being heated by components is being removed quite fast, replacing heated air with fresh ambient meaning the temp of ambient air plays a big role in cooling. None of the case fans are blowing directly on components, that's up to the cpu/gpu cooler fans and their effectiveness. I could be wrong but I think they have a pretty good supply of fresh ambient air. Only when I'm running a stress test like p95 or ibt does the air coming out the back of the case feel slightly warm and that's most likely from my air cooler blowing directly at it from about 2" away.
Each case and fan type/speed, location etc will have a different outcome on cooling but bit-tech did a test using a fractal define r3 and various fan placements with 0-6 fans. While cooling improved some with each addition of fans, they found it hardly improved with over 3-4 case fans and quickly showed diminishing returns with 5-6 fans. They did add more noise as well as higher expense for the additional fans. Throwing as many fans on a case as it will hold doesn't always mean the best cooling vs fewer well placed fans.
http://www.bit-tech.net/hardware/2012/02/10/the-big-cooling-investigation/10
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