I'm thinking of upgrading from my Geforce GTX 680 (2 gigs) to one of the new 690's (4 gigs).

Has anyone else made a similar upgrade (from a 680 to a 690) and how much of a difference did you notice in Skyrim? How many mods do you run with?

http://www.gamesas.com/topic/1435536-the-community-tech-thread-no-124/

You want that thread for shopping help.

To answer your question, you won't see much of a difference. The 690 still allocated 2 GB for each GPU, so you still only have 2 GB total of VRAM.

Along with that, it's not much different than running 2 680s in SLI. Dual GPU cards are for those who don't really want two physical cards. However, two physical cards generally perform better than a dual GPU card.