I got the Valve Index on Thursday, aside from some driver issues the main difficulty that I ran into is that their Display Port cord is near the upper limit of length to run at full 4k 60htz.
This likely is causing some of the sparkle and connection issues that people have been running into.
There are several active DP cables available for lengths from 50′-100′ and some fiber conversion cables as well (with more cost). I ended up trying out a DP repeater instead however and a 10′ DP 1.4 cable for the initial card to repeater connection and they work wonderfully.
Figured I would shout out the one I found and am currently using in case it helps anyone else out: https://www.amazon.com/gp/product/B01IE3IAIS
The manufacturer claims a 500 picosecond latency.