so is the main limiting factor with wanting to do multi-monitor settups the amount of dedicated video ram rather than raw power? Obviously more of each is better, but does one weigh in more heavily or are they pretty even? Would a single 4gb 670 be able to handle 5760x1080 for most games at ultra/high settings?
Raw power is still the main factor, but if you raise some of the settings, like AA, it can, in some games, hit a wall, and the FPS would plummet. In most cases it won't, but games like BF3 will require you to lower some of the high end settings to keep the Vram usage in check. Given the power of the 560 ti's, you'd likely have to do that anyways.