I have swapped onto another PC with RTX before RTX support was added onto ue4, so i have not got a chance to test this, Does editing raytracing settings crash your game or do nothing at all if done on a system that does not support raytracing?
Edit: There have been 25 views, all im asking is if you crash or not if you type something like r.RayTracing.AmbientOcclusion 1 into your console (with ~ for newbies, Default RHI needs to be DX12 and Raytracing needs to be on first, both in the project settings search bar)
As to direct cause and effect no one really know as raytracing for the purpose of a video game is still very much a first adopter feature as to the needs of a real time raytrace better suited for enterprise purposes. There is just no yes or no answer if RT is used where the hardware does not support the feature and will take time for new tech to migrate to the top of the list that would make RT based games worth the development time and cost.
So yea I would expect a lot of crashes from 1st generation RTX based cards and as always it seems that the first adopters are considered as part of the QA process and since as a feature RT is hardware bound to NVIDIA it has the same issues as to limited use of hardware base physics.