Is SLI worth it?

Solution
Its only worth it if your 780 is significantly underperforming for your needs, otherwise no.

Also I wouldn't upgrade to a 970 as suggested above, the benefit is too small to justify the cost


I was thinking the same thing. I guess I could use the money I was saving for a new power source (mine is 7 years old!) some more ram (already running 8GB) and a new SSD.