@Eddy @Mark Fuller I did more tests today and the conclusion is the same. I made sure to measure with both Afterburner and GPU-Z (Afterburner screenshot attached). At start of the race, the PCI-E bus usage spikes up for a second, but then quickly settles to 1-3%. I went back to Nvidia driver version 399.X and bus usage returned back to around 30%.
I went from a 1080ti to a 980ti ( long story ) 980ti matched much more nicely with my cpu , little difference in performance Next time I’ll upgrade my cpu before gpu ( 2600k @ 4.8ghz watercooled )