I built the following rig in February.
 
Intel Core i7-6700k, MSI Z170A Gaming M7, 16GB Corsair Vengeance LPX, Corsair H100i V2, Samsung 950 PRO NVMe 512GB, EVGA GTX 980Ti 6GB, EVGA SuperNova 850 G2, Corsair 750D Airflow Running 64-bit Windows 10 Professional.
 
I just recently bought my new Samsung S34E790C 34" monitor to go with this system.  The best frame rates I seem to achieve in any game at "ULTRA" settings is around 30 to 35 FPS max.  I have to turn the settings down to medium quality in The Division just to get it to between 50 and 60 fps and Witcher III was no different.  I play many other games (DDO, ROHAN, STO, D&D Neverwinter) and regardless of whether the graphics are outdated as in DDO or really good as in Witcher III, I always have to turn down the settings to make the games playable.
 
A lot of the research I did on this card when I purchased it back in February, led me to believe this card was capable of playing games at 3440 x 1440 at high or ultra settings while still achieving respectable frame rates.  Unfortunately my own personal experience leads me to believe that I somehow read those articles and reviews wrong.
 
Will the GTX 1080 do any better job of rendering the games I play at high or ultra settings, or did I just upgrade my monitor for no good reason whatsoever?

a google search of you monitor says its a 60 HZ monitor. So set it to 60hz and you should be able to easily hit 60FPS ultra settings on most games. 
 

Definitively SLI from 980Ti should do the job, however if you wish avoid multiGPU solution i would consider new Titan X Pascal. In some games this beast push almost as my TXM in SLI ;)
 
Ashes of Singularity (not the best title for NV) in 3440x1440

 
Rise of Tomb Raider, mediocre multiGPU scaling, but enough to play it with all its glory. 

Thanks for all of the replies.
 
The frame rate in Windows is set to 60Hz.  From the looks of it I'll be dialing back on the anti-aliasing and looking into upgrading my video in the future.