My 2080 ti has given me trouble recently because of the high vram to gpu usage in beam mp. It will stay at stock speed while it uses 8gb of ram. It will get 15 frames and I tried a ddu and reinstalling beam mp. I also played the normal beam ng and that worked perfectly. (Beam mp is a multiplayer mod for beam ng). I tried my ASUS GTX 770 directCU II OC 2gb gpu and that worked perfectly fine. Also my temps are still high after another repaste. I can’t afford ptm7950 so I used Noctua-H1 thermal paste and it was at 70 degrees Celsius in beam ng with an overlock.

making sure the cooler is sitting flat & making good contact with the GPU die is crucial, also the entire GPU die needs to be covered with paste
 
if you replaced thermal pads on the card - they need to be the correct thickness & hardness .... pads that are too hard or too thick will prevent proper contact between GPU die & cooler
 
Have you confirmed fans are spinning on cooler?
 
Set a custom fan curve for better cooling.
 
 
case fans, you need to get the hot air out of the case before the GPU recycles it?

using OC software, try limiting Voltage to GPU to between 90% - 95%
 
The lower V will reduce temps & usually does not impact performance much; because, Nvidia Boost will clock a cooler GPU faster