Right now, the GeForce GTX 700 series only reaches down to the GTX 760. Everything below that is 600-series territory. This doesn't matter very much, obviously, since both product lines are based on the same generation of silicon. Nevertheless, if we're to believe the folks at VR-Zone and PConline, Nvidia is about to add a new, lower-end model to the GTX 700 family.
Dubbed the GeForce GTX 750 Ti, this unannounced card sounds like a strange hybrid of the GeForce GTX 660 and GTX 650 Ti. The GPU-Z screenshot posted by PConline lists the same number of shader processors (960) and textures filtered per clock (80) as for a full-fledged GTX 660, not to mention higher core clock speeds (1098MHz base, 1176MHz boost). However, the screenshot suggests that, like the GeForce GTX 650 Ti, the GTX 750 Ti has only a 128-bit path to memory, a 5.4 GT/s memory speed, and the ability to filter 16 ROP pixels per clock.
There's no telling how accurate those specs are, of course. Their source is, after all, a Chinese "DIY forum," and the 3DMark scores in the forum posting—P4188 and 3170 for the Fire Strike test—seem much too low for a GPU with the aforementioned specs.
Still, the guys at VR-Zone do seem to think the GeForce GTX 750 Ti is on the way, and they expect an official announcement from Nvidia on February 18. We'll probably find out more in the next few weeks, if this thing really is coming.
VR-Zone also adds that "rumor and speculation" previously hinted at a GTX 750 Ti card based on Nvidia's next-gen Maxwell architecture. However, the site says there's "no evidence to substantiate that claim." The specs posted by PConline are certainly consistent with a product powered by Nvidia's existing, Kepler-based GK106 chip.