Looking for an upgrade to my GPU setup in my PC.  Currently I have 2 GTX580s in SLI and was looking for a single card setup to save power and hopefully not lose too much performance on them.  I dont want to spend more than $400 but if it will allow me to continue to play games at 5760x1080 like my current setup is I will spend a little more.  

Any suggestions?

Just looking at this graph http://www.geforce.co.uk/hardware/desktop-gpus/geforce-gtx-780/performance

You are going to struggle to match the performance of 2 580s in just 1 card, especially at $400.

A 770 may just about match the performance and that is just over $400. I think you are going to struggle to get great performance across 3 screens with that, but it should certainly be alright.

The 770 is the card that I would be looking into if I was you

What Munkeh said and what is your reason to upgrade at the moment. I think the next generation Nvidia cards are coming next year. So they'll be significant upgrade. As of now GTX 770 and AMD 7970 would be around are your budget as most powerful cards. 

The year after more new cards are coming.... There are always new cards coming and now is a decent time to buy as all the top end cards are out and have decent avaliability

Yeah I'd wait another gen. 780 in SLI will give you a lot more performance than 580sli, but its 1300 dollars. 780 like performance this time next year should be 350-400 bucks... You'd still need two in order to blow away your 580s.

Do what every PC user does when they want more performance. Overclock!

2014, too early right now. Keep your setup for now and wait for Maxwell level GPUs next year.

Alright, i will probably wait it out for a little longer then. Maybe then i will have a better budget to play with as well.

@disolitude

I've never had the best of luck with overclocking. I have my CPU overclocked but it is just from software that came with the motherboard and most people in forums claimed it was safe even with stock cooling as it wasnt very extreme (3.07 to 3.70 GHz).

Plus, even though I doubt it matter much, but the GPUs are supposed to be factory overclocked. By how much I am not sure. Nor would I know how to even go about overclocking them.

You have 2 GTX580s in SLI... so wait early 2014 for the next generation of AMD and nVidia GPUs.

Yeah but the GTX 700 is part of the same gen of GTX 600... the next arch is new.

He have 2xGTX580... can wait some months for a better card.

I thought it went from GK104 to 110 or something, though I guess that isn't a huge leap. I haven't been paying 100% attention since my 670 is running very nicely and I won't need an upgrade for at least another year