780 6GB SLI or 780 SLI?

You should see what happens when I overclock it! c:

 

That's all well and good but the discussion is 3gb and 6gb 780. TBH my recommendation is to wait for Maxwell instead of buying gk110 this late in the game.

 

Correct, right now. But most people don't build for right now, they build for the future. My goal and advise will always be to build for the future to get the most out of your money, unless that person has an endless pool of money. or advise to build to a particular person's situation and what they are trying to accomplish.

You are correct, going SLI with lower VRAM is ludacris with high resolution monitors. Personally I would never go below 4GB of VRAM ever again. That is why I did not make the jump to the 780Ti. For antihero998's situation, going QHD, I recommend the 780 6GB SLI all day.

 

Yes, making the jump to QHD would be best suited to wait for Maxwell as more than likely these cards will be seasoned for it. Myself, I will be waiting on the 9 series before I jump to QHD.

 

Not necesarily - the smaller bus Width (880 has a rumored bus Width of 256 bit, while a 780 ti has a bus Width of 384 bit) will likely make the Card scale worse with higher resolutions.

As in at 1080p, 880 will be 20% faster than 780 ti, but at 4k they could possibly be at the same performance level.

 

Which is all true if the rumor holds, but it is just that as of right now..rumor. Even if that GTX 880 comes out with a 256 bit bus width, Nvidia has addressed the fact that they can use less memory bandwidth with the higher L2 cache in Maxwell with similar performance.

 

Yes, its all rumors and claims atm, which are all unproven - just like that the larger L2 cache should give a small bus Width the same performance as a large buswidth (which i personally think sounds like BS, but time will tell).

 

Bus width is only one piece of the puzzle. Low bus widths can be combated with high memory clocks. Also, don't forget that the GTX 880 is rumored to have an ARM coprocessor, which is said to help provide additional bandwidth to the card.

The controversy over the GTX 880 having a 256 bit bus seems largely blown out of proportion. Just because its 256 bit doesn't mean it'll be a bad card. If you look at 4k benchmarks comparing a 770 to a 780, you'll find that the difference in performance is roughly proportionate to their respective performance at 1080p and/or 1440p.
http://www.anandtech.com/show/7492/the-geforce-gtx-780-ti-review/4