I think that is just allocated memory. As was mentioned earlier though, the limit to performance at this resolution is not really that amount of VRAM available (or allocated) but the memory bandwidth.
That is where the 770 will be outperformed by the 7900 series and the 780. This is hard to find in reviews as when this is the issue they will usually omit results or blame something unrelated.
I run 3440x1920 and I had 660 Ti in SLI a 192 bit bus, so there the problem was even more exaggerated and at that resolution a single 7970 out performs the SLI in cases where the bus is saturated.
Will it be a huge difference going from a 256 bit bus to a 356 bit? Maybe, but I will tell you from personal experience that there are few things more frustrating then getting single digit fps on an expensive gpu set up.
This image shows the problem perfectly once you put 8x AA the memory bus cannot handle it.
had 2 images titled untitiled, so this can stay (Click to show)
When we moved over to NVIDIA Surround gaming on our 3-panel setup we encountered really bad performance and a gaming experience that was unplayable. We contacted NVIDIA to let them know about this situation over a week ago and they never got back to us with an answer as to what is going on.
That review is from http://www.hardwareheaven.com/reviews/1761/pg10/nvidia-geforce-gtx-770-graphics-card-review-msi-palit-and-zotac-far-cry-3.html
and shows that if you reduce the AA to 0 you can review around the problem.
Both reviews used a 3960x
If you are really looking to run max settings at this resolution you REALLY
need a bigger bus.Edited by Rickles - 7/16/13 at 12:56pm