bryjoered :
The main issue right now is that the cards just simply don't have enough VRAM for the games that have been coming out. Even with the 780/780ti coming with 3gb it simply isn't enough at higher resolutions and antialiasing, even at 1080p for some games. If you're going to buy a card right now, get one with at least 4gb of VRAM. At the high end I think really only the Titan Black is worth it right now, the sweet spot is the GTX 770 4gb. AMD cards typically come with more VRAM. I fully expect the 800 series to have 8gb of VRAM. The issue is that the developers are using the new console's huge vram capacities to make up for their general lack of pure processing power, in comparison to modern high end GPUS. DO NOT, I repeat DO NOT buy a 780 with 3gb of ram right now!
A perfect example is Watch Dogs, which uses over 3gb of VRAM at ultra texture settings, and that's even before you crank up the MSAA. There is a clear and noticeable difference between high and ultra textures as well. Another example is Titanfall, while looking like a turd the majority of the time uses a huge amount of VRAM. COD Ghosts does as well and even the new Wolfenstein. It's a disturbing trend, that even a graphics card like the 780ti can't max new games because of limited VRAM.
Waiting for the 800 series would at least assure you that you wouldn't be lacking in the VRAM department for awhile, I would even opt for the higher end VRAM card out of the 800 series. Getting the 2gb 670 last year turned out to be a bad decision, always go for the max VRAM. Sure, you don't technically "need" it, but it could add a lot of longevity to your card.
3 GB of VRAM is certainly not ideal however the picture you are painting is not entirely correct in my opinion.
For 1080p 3 GB of VRAM is enough in my opinion, I have never encountered any VRAM challenges at this resolution
except for watch dogs.
I've never read a article claiming that 3gb is not enough except for watch dogs.
Watch dogs is the first title maxes out or exceeds the 3 GB Frame buffer @ 1080p with extreme settings.
Even when all the VRAM isn't used stuttering occurs however this is reduced when playing in offline mode.
Ubisoft will release a Patch and work with Nvidia and AMD to resolve these problems.
People with Titan blacks experienced Lag with this game and a patch is on the way
AC4 had problems in the beginning when PhsyX was introduced and now it's very smoothly with powerful hardware.
The reason for these problem is because ubisoft was overwhelmed with the multi platform launch and it seems they
were more focused on the console Architecture which has 8 gb of unified memory.
"Based on ubisofts statements"
COD ghosts also uses lots of VRAM however 3 gb is enough for the game @ 1080p.
COD ghosts is a console port that was never completely fixed beyond the 1080p resolution based on my testing.
I play both Titanfall and Wolfeistein @ 1440p maxed out and I'm fine with my 780 ti.
The 780 ti is incredible at both 1080p and 1440p.
The 780 is good too and provides an excellent experience at 1080p.
"EXTREM SITUATIONS BELOW"
The Challenge with 3gb of VRAM is when you want to play Bf4 @ 1440p with 150+ scaling in SLI to give you one example.
Playing games at 4k will also present a challenges with a 3 gb frame buffer in some games