You can max out this game on a GTX670 with ALMOST the highest settings.
You can max out this game on a GTX670 without the HD texture pack. Most of the time I max it out with my GTX680 (TOP version) but I get occasional drops to around 50FPS (with the HD texture pack).
I can also almost max out this game, but if I want a solid 60FPS I'd have to drop a few things just slightly.
if it was up to me to get a 680, id get the msi lightning 680. 2 slot and its cooler than the asus 3 slot (or so i heard)
The GTX 680 TOP (1139MHz version) can't be beat for performance and noise. It's only drawback is the 3-slots but the reason for the great performance and noise is the extra heatsink cooling provided by the extra volume of three slots.