Or if you have multiple monitors.
This is true also; But if you're looking at doing a multiple monitor scenario, you could also do yourself the justice of spending a little bit more (if it's within your budget) by getting the GTX Titan, or waiting to get the Titan Black Edition.
Not only would you have drastically increased performance and computing with consistency, greater than the GTX 780 Ti (with multiple monitors)
if you go for the 6GB GTX Titan Black Edition, but you wouldn't even need to worry about games that don't even support SLI/Crossfire, nor would you have to worry about microstutter issues from running two GPUs.
You could even go for the GTX 780 Ti (cheaper and benchmarks better than the GTX Titan) instead of going for two of the same significantly lesser-quality card (GTX 770) just for SLI.
Going SLI is great and all, if it's supported and you don't experience any microstutter, but if you find yourself having to turn off SLI then you will likely find yourself disappointed when you've spent good money on two cards and can't even use both of them. I say if your plans are to go SLI and are willing to pay $600 or $700 USD to get two 770's, you might as well just get a single GTX 780 Ti or go for a little bit higher and shoot for the GTX Titan (runs better than the 780 Ti when gaming or computing on multiple monitors). It'd also be more 'future-proof' to do it that way.
I hope you don't plan to make this GPU upgrade and are only thinking of increasing performance on Battlefield 4, and aren't even considering future-proofing. There are plenty of options for $600-$700 single GPU solutions, that you can even run SLI with later on down the road and do much better than a GTX 770 2-Way SLI, that are more 'future-proof' and are better options. Currently, the GTX 780 Ti is the absolute best single-card solution currently out on the market; and it's price

erformance ratio even beats the Titan by $300. For the price of two 770's on SLI, that indeed presents greater risk (microstutter issues, SLI incompatibilities, less 'future-proof', etc), you can get just one GTX 780 Ti and benchmark much better - and STILL go SLI.
On the other hand, you could also decide to stack your money and wait for one of the higher end Maxwell (GTX 8xx) GPUs this July, and get another monitor or two at the same time.
When the Maxwell comes out, do you know what's going to happen then? Two things that are really going to piss you off: 1. The prices you paid for your x2 GTX 770's are going to drop significantly and cost next to nothing, when you could've been more patient & waited for the 800 series and get much better performance for an even lower/equal price than the current cost of getting x2 GTX 770's; and 2. Newer games are going to have hardware demands that are going to end up leaving you in de_dust. The GTX 770 is already bottom-benchmarking in Battlefield 4 (see list below). The GTX 780 Ti will still be one of the very top cards by itself, and you will still have room to get a GTX 800 series if you so choose (when the time comes). See
Law of Diminishing Marginal Returns; Do you really want to pay that much for something that will serve you significantly less, when you can go for something much better at the same price (780 Ti) or just a bit more (GTX Titan)?
Ultimately it's your call to make, and it's for you to decide what you feel is most worth it to you. All anyone else can do is tell you what the many options and consequences will be for going either route.
In any case, here are the Battlefield 4 benchmark results for the GPUs mentioned in this thread:
Keep in mind the Radeon HD 7990 and the GeForce GTX 690 are dual-GPU cards (also affected by microstutter). Your GeForce GTX 770 is at the very bottom of the list while the 780 Ti is the very top single card solution. Two 780 Ti's (2-Way SLI) annihilates all of the cards on this list.
Also remember that:
- The more GPUs you are running together, the more prone to microstutter you are.
- The less GPU power, the more prone to microstutter when running multiples of the same GPU.
- The less computing power/capability, the more prone to microstutter when running multiples of the same GPU.
- VRAM doesn't stack.
- FPS and computing are two different things, but are both very important; especially if you plan to game on multiple monitors.
I guess my thinking was that if I did end up getting another GPU it would lead to me spending more money later on for the same monitor I have now. I guess I should have said that was my intention if I did get a second GPU.
Yes, you should have - to help us to better assist you. However, you did yourself a service by clarifying; Now you have more than enough information to make a wise decision.