Just an FYI the performance hit you take going to extreme resolutions in video games is a problem with all PC's.
Even a 680GTX will have it's work cut out playing games at 2560 x 1440 with maxed out settings (depending on game).
"Generically" speaking when you have a multi-monitor setup or 2k or 4k resolution single screen...and you want to do simulation or video games graphics
using the full resolution available to you... it benefits you greatly in having multi-video cards running (SLI or Crossfire) on your setup because you are going to need a lot of extra horsepower.
I of course am not saying multi cards are needed to run high resolution... it's just beneficial if gaming/sims at those extreme resolutions is the goal.
If all you want to do is run Photoshop or video editor with lots of screen real estate... you should be fine. You can always run games at lower resolutions on your hi-res screen... which can look ugly due scaling up pixels bigger than they need to be to fill out the screen. The alternative is always force your games to run in windowed mode and deal with the extra space around the game window (can always set desktop to black to make it easier on the eyes).
You have to keep in mind that extreme setups require extreme solutions if you want them to be top performers. (keyword being "if")
To use an analogy...
It's kinda like buying a Lamborghini body without the engine and expecting a cheaper smaller replacement engine vs the high end lambo engine will be good enough and saves on cash..... It looks great on it's own and you can definitely use a smaller engine block and make it run. To most people that will seem just fine (all looks and it still works too!)... but when it comes to real performance demand, the little motor will just not be there for you to dish it out for you.
PS: I don't wanna com across knocking single GPU cards running 2-3 monitor setups or knock high end Dell screens. My primary work rig has a 30" Dell IPS being run by a single nvidia gpu (580gtx)... I just don't use that box to game with it all... games choke at that resolution... but the screen is amazing for doing graphic works on it and browsing the web. I also run 2 monitor setup on my main "fun" rig and it's not SLI either... when I game I usually just select my middle monitor so I don't have to scale out the resolution out to both 1920x1200 screens .. which ends up being = 3,840x1200 desktop resolution.
I just wanted to let you know that with these kinda monitors you gotta stay realistic with your expectations.
PC Setup:
Battlestation Setup: