On Ubuntu with 1080Ti version 5 is 0.5% slower than version 4
Just wondering which release of Ubuntu are you using and what is your driver version? What is the spec of the mining rig? Does the card sit on risers?
I have tested the 5.0.0 release on machines that have risers and the one that does not. I did not notice the performance difference.
This is on Ubuntu 16.04 with driver version 384.69
Spec is 6 x 1080 TI cards all on risers.