Cioby :
Older generation GPUs are sold at the same price as they were when they launched (more or less). So it's usually not a good idea to buy older generations. TitanX tho is almost as good as 1080 and 980ti. But you're better off buying a Titan XP which is newer and the same price. Tho the 1080ti is better for gaming.
980 ti is good and all, but it has much less performance compared to say a 1060, then 170, then a 1080. I don't personally know about the titan X and 1080 benchmarks, never owned one, but I have a friend with a 970 and a i7 5th gen, I had a 1060 with an i3 4th gen and I out perform him in every game (both skill and benchmark). I don't mean to throw shade, i'm tired r n, but use this to be informed; just because it's good, doesn't mean it can be on an equal ground...