With a 1080ti, 2.7 GB of VRAM is unavailable. This seems to be a known bug (reports dating back a year ago) and apparently both nVidia and Windows are aware of the problem:
https://answers.microsoft.com/en-us/win ... 292&auth=1
viewtopic.php?f=12&t=51992
Is there any update on this? It must be a big deal to Otoy.