I have recently upgraded to a 2560 x 1440 monitor and am now hitting my VRAM limit in some games, I have 2 x GTX 570's 1.25GB. I have thought about selling both 570's and buying a 680 but am not sure if it will be worth it. If I turn AA off I don't hit my VRAM limit, I would not have this problem with a 680.
I am concerned that a 680 will not be as powerful as my 2 x 570's and I can't afford 2 x 680's, I don't want to sell up and be disappointed with a single 680.
Has anyone made a similar upgrade? If so can you let me know how it went?
The problem with 2 570's in SLi is that you only get 1.25GB of vRAM. You don't get to use all the vRAM from both cards, SLi and crossfire don't work like that. If you're having trouble with VRAM limits, and with modern games this has become pretty common, I would recommend the most powerful 2GB-6GB GPU you can afford. To me a 680 would be an upgrade over 570 sli because increased vRAM and drastically reduced power consumption and heat. Either way you should be able to max out whatever games you're trying to play. With a 670 or 680 you wont have vRAM issues. Also you could look into the 7970 that are cheaper and perform equal or better in almost every title.
Nvidia has been stingy in VRAM area. I had (and still have it lying around) 570. When I installed texture mods on Skyrim, the performance tanked a lot even at my 1680x1050 without AA. Now I have 7870 2GB and use even more graphic mods. Let's just say, the difference is night and day. I probably have more than twice the performance I had with 570. Haven't dropped below 30 fps even once and more than 50 fps most of the time. Even now I use almost the entire 2 G of Vram.