I use a 1080ti in a similar rig. I had some issues when I built a newer machine with a Gigabyte MB, 2080ti. I recall using some clocking and GPU configuration software to find a balance of performance/stability.
Are you running #Windows10, or #Linux ?
Your PSU sounds capable. There might be some stress testing software which might help to identify if there is a #GPU memory, or other issue.
Hopefully someone else will chime in and help.