If this is the temp you have on full load then that’s really amazing good temps… Water Cooling is for sure the best way to go for a cpu like yours…
I had awso crashing problems with dx 12 when i rendered a scene and it aways crashed so i had to switch to dx 11 then everyting worked fine. I found out it had to do with the “texture streaming” option which solved my issue and i could then render just fine in dx 12…
You can check it out if you want is the last post for the solution i found but was only for rendering…