7970 for sure. Although multiple gpus run multiple monitors at higher rates, Crossfire (and SLI) just don't work that well all of the time. They have driver, game and microstuttering issues (if you are able to see that, not everyone does). I have used Crossfire and SLI and never recommend them unless you are looking to do benchmarking or (in your case) multiple monitors. Even so, you may run into issues, so I say get the fastest single gpu you can get and that is this one http://www.newegg.com/Product/Product.aspx?Item=N82E168....
Keep in mind 4k tv's will cost $10-30k (the Sony is $25k @ 84"), and 8k will run well over that. Also the 4k is 4x the resolution of 1080 and the 8k will be 16x. More than likely the 4k gen will be short due to 8k tech already out, but too expensive. Around 2020 they're expecting 8k to be available. So don't focus on these for your future gaming experience, just stay on the eyefinity.
The Tom's stuttering article found that microstuttering ceased to be a serious issue with cards above the 6950 level.
If you want to max games on triple monitors, you'll need two 7970s.
I just read that article and here are the closing thoughts. Sure, you'll see less stuttering, if you are able to see it in the first place, by putting two ultra high end cards in your system, BUT, I would not pay a thousand dollars or more to find that there are still issues, even if they are smaller issues. That doesn't include the driver problems or game incompatibility either.
"Frankly, there haven't been any revolutionary developments in the fields of frame rate consistency and micro-stuttering, even though we have seen improvements from Nvidia's drivers. At this point, neither competitors can claim to deliver a 100% stutter-free gaming experience with two GPUs working cooperatively.
Bearing in mind that vendors purposely try to price two mid-range cards similarly to a faster single-GPU board wherever possible (generally, when the competitive landscape allows for it), we’d have to pick the single-GPU card every time. The three-way setup based on a trio of mid-range cards is the pièce de résistance. But AMD and Nvidia also know this, and purposely handicap their less-expensive boards with just one bridge, limiting configurations to two boards. The way around this, PowerColor's Radeon HD 6870 X2 bears its own significant price premium. It's also not a quiet board, and it requires a bit of faith on your part to trust that CrossFire profiles will continue to incorporate support.
We learned one other thing from our experimentation: the faster the linked cards are, the less you see side effects from teaming them up. This precludes using two low-end cards. CrossFire and SLI only make sense from the mid-range and higher, with a slight advantage for SLI. That makes both technologies a lot less interesting for upgraders and bargain hunters. Again, given comparable pricing, we'll take the single-GPU card any day. And even then, not having to worry about micro-stuttering would compel us to pay a little more."
Definitely the 7970
I have an MSI 7870 myself. It's a fantastic card, just looking for a little more power as you are. Went and grabbed a 7970 and am very impressed with the performance. This whole gtx 680 vs 7970 crap is bs. The differences are so minute that you wont even notice without an FPS counter. Yet people want to whine about a 3 FPS difference. On the matter of 4k TVs.... You would be completely and utterly wrong sir. You can get a 4k tv for a little over a grand http://www.amazon.com/dp/B00BXF7I9M/?tag=googhydr-20&hv...
Yup. Although you would need one hell of a card setup to be able to utilize that resolution. Given your card even supports it at all. I would make sure before you purchase anything.