No it is not worth it at all, a 660 Ti is a 670, besides the bandwidth. The 660 Ti has 192, and the 670 has a 256. Other than that they are completely identical. There is a 5-10% increase in performance but that isnt noticeable at all. An upgrade would be either to SLi the current 660 Ti, or upgrade to a 680-690. But to upgrade to a 670 is not worth it at all.