We haven't heard an awful lot about the GeForce GTX 980 Ti yet. A couple of weeks ago there were reports that this card was slated for a launch after the summer but now PC Games Hardware reports the card may be announced at Computex (June 1-6). The site claims the launch of the GTX 980 Ti was delayed from May to early June for unclear reasons.
The GTX 980 Ti is expected to feature the GM200-310 GPU but its unknown how this revision differs from the Titan X's GM200-400. Price-wise the GTX 980 Ti will fall between the regular GTX 980 and the Titan X.
Nvidia’s partners will be allowed to design their own printed circuit boards and cooling solutions for the GeForce GTX 980 Ti. If Nvidia announces its new graphics adapter at Computex, actual graphics cards will be demonstrated at the trade-show. Unfortunately, it is unclear whether manufacturers of graphics cards will demonstrate their own versions of GeForce GTX 980 Ti.
There are also strange rumors that NVIDIA is working on a third GM200-based consumer card that may be named GeForce GTX 980 Metal Edition. This is supposedly a cut-down version of the GM200 with a price and performance higher than the GTX 980, but that would make NVIDIA's high-end lineup awfully crowded. Guess we'll have to wait a few more weeks for a clearer picture.