[citation][nom]wolfram23[/nom]I always find it almost shocking that the 6950 1gb and 2gb models have basically identical framerates even at 2560x1600 in all of these super demanding games. Do we really need more than 1gb VRAM? I always think about going triple monitors, and always think my 1gb is going to be a drawback...[/citation]
2560x1600 is 4mp whilst 3 1080p monitors is 6mp, a 50% increase. This makes a significant difference especially if you enable AA options. On a xfire 5850 setup I used to run, several games simply would not run at all (Shogun 2, GTA IV, Crysis come to mind) at 3240x1920, but would run fine if I lowered the resolution. Switching to a 2x 2gb 6950 setup allowed 3240x1920 to run.
Remember, most review sites simply do no do multi monitor reviews. If the cases where they are done, like the below HardOCP article, there are very clear cases where VRAM walls are hit in triple monitor gaming. In this specific case, tri fire 6970 were able to beat tri sli 580's simply because the 580's didn't have sufficient VRAM even with 1.5gb.
Is VRAM an issue at 1080p? No. Don't bother worrying about it. However if you're using multimonitorssetups, it makes a big difference.
http://hardocp.com/article/2011/04/28/nvidia_geforce_3way_sli_radeon_trifire_review/2