I went from an AMD 3600 6 core and Radeon RX6750XT to 5800X3D and RTX 4090. I see a significant use of VRAM well past the 8GB of your 3070ti. My 6750XT has 12GB and I used easily 10GB and the 4090 with 24GB still uses only 10-11GB VRAM with TLOD 200 World Scall 100% TAA etc lots of ultra 16X 8X8 etc. My CPU jump from 3600 6core to 5800X3D sees frametime drop below that magical 11.7ms very consistently. This is a huge improvement from the AMD 3600 CPU. The Combination of a CPU feeding the GPU and having enough VRAM to “buffer” the frames smoothly makes all the difference. Regardless of settings in MSFS, 6700K + 3070ti will work but you have to find a way to set MSFS to reduce your frametimes on the CPU and then maximize your GPU utilization. For a smooth experience Frametime is key. I would think upgrading a 6th Gen CPU to current whether AMD or Intel will allow you to feed steady frames to your 3070ti. The 3070ti will still be a problem on HP Reverb G2 due to a near 4K image that is limited by 8GB of VRAM. Devs are really struggling to get this level of realism inside 8GB of VRAM. With my 5800X3D and 4090 I pretty much fly everywhere at 45FPS+ with GPU headroom and 11ms frametimes from the CPU in TAA 100% world Scale and TLOD 200 OLOD 200, except NYC, London etc at 30+ FPS in VR.
TL;DR Upgrade the 6700 CPU first!
I going to say it doesn’t matter what GPU at the moment if the core of the game does not support VR fully. I have 4080 and it works, but not as you would think it should. I thought when I got the 4080 my worries would be over and I could just play as intended. However it feels as if it’s just not enough in VR.
sadly there is a huge difference in performance from 4080 to 4090 and specifically in VR due to the high pixel count and target refresh rate of 90Hz. Barrel distortion calculations making for larger fields of view to calculate over 2D 4K etc. Based on the target of 90FPS even the 4090 doesn’t average much over 100-110FPS in 2D. I bet you 4080 looks amazing in 2D. I play in 5120x1440p on 49" ultrawide for 2D and it’s butter. Going to Reverb G2 V2 with HAM removed I get to see the most I can and the 4090 keeps up with all movement. I agree VR is pushing every limit it can on CPU and GPU. There are VR games less CPU bound and work incredibly well. This is the curse of MSFS.