What should I upgrade to?

[Solaris]

I currently have a GTX660, which was fine when I was running one monitor in 1920x1080.

I then bought 2 more monitors, and started playing with NVIDIA surround, but have had to turn down my graphics settings on some games to keep up with the three screens.

So.. I have a 550W PSU...

Do I

1) Get a GTX680 and sell the GTX660?

2) Get a second GTX660, set up SLi, and upgrade to a bigger PSU (850W or so)

Both will cost a similar amount, just can't decide...

Or, what AMD options do you recommend?

 

[Solaris]

Why not a 680?

 

[Solaris]

Antec VP550P - http://www.antec.com/pdf/flyers/VP550P_EN.pdf

But I'm also running the AMD FX-8350 which is a fairly power hungry CPU.