Whats $1500 when you bought a Titan V and 7980XE? Chump change!
Go for a 64GB 8X8 kit. That will cover about anything you can throw at it.
Im running a 64GB Corsair dominator platinum 3800MHz kit and it does XMP at the full 3800 and even went to 17 on the CAS instead of the 19 that is the XMP. CMD64GX4M8X3800C19
I gave the Titan V a passing thought but 2x 1080Ti is SLI will match the performance for less than half as much. I paid $1500 for both cards. This and the fact that even Nvidia said the Titan V is not for gaming, more built towards mining with much slower clock speeds.
“Two things are infinite: the universe and human stupidity, I'm not sure about the former” ~ Albert Einstein