lehpron
Historically, achieving max/ultra details smooth in modern game title has always been (and may remain) an exclusive reign of the highest-end product.  If anything less could achieve max/ultra smooth with modern games, why does expensive need to exist at all?  It has a purpose, but only you can justify it.
 
GTX970 is around 15% slower than GTX980 at >30% less cost; so manually overclocking the GTX970 would make the most financial sense, but overclocking isn't guaranteed.
 
The following is the kind of analysis I expect you to do next time a question like this arises.  First, you Google the graphic card you want to know about using the keywords "review" and the game you would like to know about.  Then, sift through the results and find a review that covers your game, then do what I did below:
 
Speaking strictly of Crysis 3 at Very High details:
 
1080p (FHD):
1x GTX970 = 42.7 fps avg
1x GTX980 = 51.4 fps avg
16.9% slower at 1080p
 
2160p (UHD):
1x GTX970 = 12.5 fps avg
1x GTX980 = 15.2 fps avg
17.7% slower at 2160p
 
2160p is four times the total resolution of 1080p, therefore in a fully GPU-bound scenario, frame rates should be 25% of the smaller resolution; but the difference of GTX970 is 29.2% and GTX980 is 29.6%.  So hypothetically, frame rate average at 1440p (double 1080p) will be just above 50%.  In the above review regarding 2-way SLI, 1080p had GTX980 scale 81.6% and at 2160p it scaled 91.4%. So at 1440p, scaling to 2-way would be in between, say 86% more than single graphics card.
 
My estimate:
For 1440p with one GTX970:  around 30's frame rate average.  
For 1440p in 2-way GTX970 SLI: around 50's frame rate average.
 
Of course all this assumes your system configuration is identical to the test configuration in the review, after all, it is your CPU that runs your games and the reason why both resolution and SLI doesn't scale 100%.

crezno
I run 2560x1440 and 7680x1440 with SLI 780 Classifieds.  On 1 monitor I can run any game on highest settings with well over 60fps seems pretty close to 110FPS depending on the game. I run vsynch so dont create unnecessary heat, but I have to turn off AA. With Aero off, across all 3 monitors its only using like 120MB vram. Some games with AA of on 1 monitor use like 700MB, some use 1.6GB etc. However, as soon as you turn any kind of AA that starts to change. my cards only have 3GB Vram, so MSAA just wont happen. It maxes my VRAM out and I get 3-5 FPS.  I have ran normal AA at 2x and have been inside my 3GB.
 
Having said that, 4GB on the 970 probably opens the door to single 1440P gaming with MFAA enabled.
 
I will also say that what Lehpron stated is probably a very close estimate.  Something to think about is VRAM. If you want to run higher resolutions with AA on, or jump to 4k, or 2d surrounds at 1440p+, you may want to wait for the next series of cards that are looking to be 6GB+ VRAM cards. Otherwise youll end up in my boat, and just have AA off for the most part.

ManBearPig
Sorry, haven't even had time to install it yet.  I work on oil rigs for weeks at a time and got it on my last job.  I got home to at least take it out of the package and look at it, but not install it.  I only had 1 day off and I decided to use it to install modifications on my car.  Already on my next job but hopefully this one won't be that long.  When I get back I plan on playing with my new 970 FTW and seeing how much I can OC it.

knowings7
A 5820k is still going to be expensive, remember your gonna have to fork over the cash for the new x99 boards and ddr4 ram isnt cheap either. It would be wise to put the extra cash you save into your gpu and go with something like an i5 4690k, on a gaming perspective of course. The performance increase you would see going with a 5820k would be minimal compared to the 4690k.

nine9s
The heat pipes were not a problem. It was not misaligned as some report stated.  It was designed for the two main heatpipes to contact the GPU, while the smaller third pipe vented overall heat away and did not contact the GPU.  
 
For example, from the http://www.bit-tech.net/hardware/graphics/2014/09/19/nvidia-geforce-gtx-970-review/3  review:
 
The way the EVGA GTX 970 ACX heat sink was designed is based on the GTX 970 wattage plus an additional 40% cooling headroom on top of it. There are 3 heat pipes on the heatsink – 2 x 8mm major heat pipes to distribute the majority of the heat from the GPU to the heatsink, and a 3rd 6mm heatpipe is used as a supplement to the design to reduce another 2-3 degrees Celsius. Also we would like to mention that the cooler passed NVIDIA Greenlight specifications.