At the moment I'm running an Nvidia gtx 2070 with an Oculus Rift S, solely running in VR. I'm looking to purchase one of the latest generation video cards when they become easier to acquire, probably be rtx 3080 which has 10gb of vram. Anyway, yesterday I spent a considerable amount of time optimising my rfactor2 and Nvidia graphics settings. I was using MSI afterburner to log GPU and CPU statistics along with fps and then analysing the results afterwards before making minor setup adjustments. I was running a 20 car grid on the Nordschlife Endurance circuit with a Ferrari f388 GTE, cloudy weather. That's probably as arduous a race as I'm ever likely to do. It proved to be a time consuming and very worthwhile exercise. I improved my game look and performance quite a bit. I also learned that with the combination above my video card is using all of it's 8gb of video ram, absolutely saturated! This begs the obvious question, when looking at purchasing a new video card the rtx 3080 only has another 2gb at 10gb. The crazily priced 3090 has 24gb. I'm assuming that the game just uses whatever ram is available and when full just caches from disk. Would a new rtx3080 be limited by ram or is this not an issue and why?
Caches from computer RAM rather than disk, I believe. I could run my triple 4k monitors on my old system (GTX 1080 and circa 2012 CPU) provided I stayed within limits (about 15 AI). Yes, all 8 GB of GPU RAM were used. All other simracing titles I've tried confine their GPU RAM usage to less than 6 GB and are presumably caching in computer RAM. I'm now running the triple 4k monitors with an RTX 3090. GPU RAM peaks at 12824 MB with 42 AI on the long Nurburgring. As far as I know, it's only the people with less than 3 GB on their video cards that have serious fps trouble. If you're seriously concerned about GPU RAM, then wait for the 3080Ti or the AMD cards which will have more RAM.
Yeah caching from RAM, but rF2 performance does take a big hit if the combined memory allocated by cars and track exceed the physical VRAM of your GPU. I think a rough estimate is that Nordschleife at 1080p max settings consumes around 3.5 GB with no AI cars. Add another 60 MB for every AI opponent you include.
Thanks for all taking the time to respond. I think that this is something I really need to get a good understanding of before buying my next video card. Being a VR user and also as I'm hoping to also upgrade to an HP Reverb G2 then the resolutions I'm running at and the texture levels are all high. I did find it odd that both CPU and GPU occupancy was lower than expected with only VRAM maxed out. I think I'll have to play around with detail and texture settings to see if I can find something that works whilst looking great. As I'm using VR I do like all the opponent cars to look good. I see no point in loading all the cockpit and internal detail though but I suspect that there is no way to selectively remove that unnecessary detail.
Note that higher resolution (SteamVR supersampling) will cause higher VRAM use (according to Afterburner). On my Pimax 5K XR I very often hit 10Gb+. What I do not know, however, if crossing the limit of VRAM allocation will cause huge perf drop. In the past, it was like that. But all this stuff gets more and more complicated. Who knows, maybe once you hit 10Gb, driver will kick out some unneeded stuff out of VRAM. Just because a tool indicates 10Gb VRAM usage, does not mean all of that data is used to render the frame. That said, VRAM usage in VR+rF2 makes 3080 10Gb not an option for me personally, it's too risky.
Take a look at this thread as well: https://forum.studio-397.com/index....rmance-guide-on-how-to-prevent-low-fps.61265/
Must admit I'm beginning to think that the 10Gb 3080 probably isn't going to be right for me. That being said the 3090 cards come at an eye watering cost. I can afford one but cannot really justify that cost to myself. Hopefully when the AMD cards hit the street and availability is better we may see some cost reduction. Regarding super sampling. I used to have SS set at 1.4 but have since found that having it set at 1.0 with the Nvidia image sharpening turned on yields similar results.
4K with gfx maxed out and 40 AIs split in GT3/GTE/LMP2/LMP3 on the Nords, max out the 11GB memory of my GTX 1080TI. That's insane when you think about it, but pretty much an extreme case.
Hopefully there will be 3080 variants with more VRAM, or AMD comes out with a comparable GPU (in VR rendering). Are you sure NVidia image sharpening really works in VR/rF2, are you using SteamVR? I was under an impression that it does not apply to VR images, but if it does that's great news.
I went into a fair bit of depth on the impact of VRAM usage, amongst other things, here: https://forum.studio-397.com/index.php?threads/fps-the-hunt-for-optimum-performance.67613/ I found that once you hit the VRAM ceiling, the impact of streaming in new information can be significant enough to make it worth reducing settings (texture quality and number of AI) rather than live with the fps drops.