https://bitcointalk.org/index.php?topic=5289066.0Low 40's is normal for the 1080ti and it will only get lower due to a known bug suffered by the 10x0 series excluding the 1070ti where it was fixed.
1080Ti has gone from 55 to 43mh in 5 years and 1070 has gone from about 33mh to 25mh.
I thought the lack of update for the 10** series is why they lose hashrate performance easily? What is this bug update that you are talking about? I doubt the gtx1080ti can use 470 and 471 Nvidia drivers, you need to download the last old driver which I believe it's the 460 series, I don't know what Nvidia did this.