I'm not sure if anyone has had a chance to properly compare the two yet, but I'm in the market for a new card. The goal is simple:
Either get a new Sapphire 7970 3gb to run in crossfire
Sell the one I have for a 6gb version (and eventually, like a few months from now, get a second)
or grab a 3gb GTX 780.
The main thing I do with them is game (preferably on Ultra when possible) so I'm trying to increase my FPS when gaming. I know with skyrim my vram gets pretty close to maxing out and prone to ctds, so I was wondering if getting xfire would solve this or am I better off just grabbing the 6gb 7970? I know vram doesn't stack in xfire (but it'd be awesome if it did).
Quick bonus question: I've noticed that if I run in eyefinity but don't enable 5760x1080p using the ini for Skyrim, I get 3 screens all playing the same game. Now, I generally play like this cause it's quite convenient: i can turn anyway I feel comfortable and still see the screen. But as I was looking for answers to my own problem (who does that nowadays?!) It occurred to me that this could possibly be affecting my card's performance. I'd hate to have to switch to one screen, but does it actually matter if I'm still using 1920x1080 res for each window?
If you already have a 7970, and you have a CPU/motherboard/power supply that are equipped to run crossfire properly, and you are playing on a single monitor so that you can take advantage of the new frame pacing drivers, then you should just buy a second 7970.
Don't worry about vram, IMO. I don't think skyrim alone is worth paying a huge premium for a 6GB card (and modded skyrim is quite literally the only thing that ever needs more than 3GB).
-edit- Just saw you're running eyefinity. Crossfire is still broken for that, so yeah... you can more or less ignore crossfire as an option.
as it stands now, the 6gb 7970 costs only 50 more so it's not that big of a premium, but patrick bought up a good point, I might as well wait for the 9000 series seeing as I'm actually getting paid around the same time as their alleged release.