My current card is an MSI GTX 580 3GB, and it has worked great for gaming at 1080P. I recently bought an HP ZR30W and now I get around 30 FPS in Skyrim on Ultra settings, 8x Antialiasing, 16x Anisotropic Filtering, FXAA, and a lot of mods. I first considered buying a second GTX 580, but I can't find any used 3GB cards. They are still around $550 on a few Canadian sites. On eBay.ca, I found a refurbished EVGA 03G-P3-1584-AR for $520, and a Classified version for $530 (also refurbished). I don't like the idea of buying another one at those prices when a 4GB 670 is quite a bit cheaper. Don't video cards usually go down in price when the next series is released?
So what I am thinking of doing is trying to sell my 580 and buying 2 670's. I've done a lot of reading and about half the people say that a 2GB 670 is good enough at that resolution, something about the 256 bit bus that limits the card before the memory. The rest say to get the 4GB. When I play Skyrim, my memory usage is often around 2400 MB, so I think I will go with a 4GB card. My options seem to be:
for anything 1440p+ I'd recommend a 7970 factoyr OC model over a 670m they are actually a lot closer in value now that 7970 is in the 410-430 range and their superior memory size & speed really helps in 1440p/1600p realm, value wise a 3G 7970 is either cheaper or the same as 4G 670. They can OC pretty well too. But if you have concern about ATI driver issue then get a 670.
It's wise to get the 670 over the 7950 due to the history of buggy AMD drivers for Skyrim. Another big plus for the 670 is the fact that it allows you to enable High Quality Anistropic Filtering, Ambient Occlusion, and Transparency Supersampling in Skyrim for MUCH better graphics. http://www.geforce.com/Optimize/Guides/the-elder-scroll...