It's probably a personal thing but in VR with OpenGL I've found the best RC8 graphics setting to be medium (actually low for trees, high for shadows) and it's VR rendering at 1.5 (basically SS = AA for VR). This always gives me a solid 90fps with my Oculus Rift cv1 in all 4D scenery and looks great to me.
Same setting so far with Vulcan enabled looks a little better and ~ the same solid 90fps in VR. I will try increasing graphics in stages and see if I can hit CTD. I have a new desktop PC with an i9 9900k, gtx1080ti, and 32gb 3000mhz ram so I probably have a little more headroom to play with.
Using driver 431.60 here (in both setups). Certainly, if I reduce the graphic settings to medium, I avoid the CTDs, but not sure if with this I'll loose all the visual quality improvements that apparently come out from using Vulkan instead of OpenGL (mainly high quality AA).
Cheers, Ed
OK, I now have tried all different graphics setting and VR settings with Vulkan and I never got a crash to desktop (CTD). This was running both VR and non-VR.
What I did find was that Ultra settings did drop my VR fps below 90fps in some areas. Fine with High settings but for me the high settings for water and tree density did not add anything significant to me.
So now,with Vulkan I have settled on high textures, high shadows, low tree density, and medium water. I also increased rendering scale ratio (SS) to 1.6. This gives me a solid 90fps in VR everywhere and RC8 VR looks fantastic.
One tip that I got from an Oculus Rift Developer a while back that might help those who get the odd CTD is to increase your windows 10 pagefile size. Only do this if you have a fast SSD drive btw. Set the minimum to your gpu's Vram (11000 mb in my case) and maximum to 2000 mb above this (13000 mb in my case). I'm not really sure how or why this works but since I've done this all my VR sims are a lot more stable.