I been tweaking DCS since the OpenXR came out and I so far been able to get the Resolution to 60% best I did on SteamVR was 20% so a very big jump.
I am also in a bind as my VRam usage at some points during gaming get over 8GB to about 8140MB, now I guess this is not good and the vram is probally dpping into my slower System RAM.
Now my question besides lowering settings like terrain and textures how can I get my VRam usage way below 8GB? I know the best solution would be to get a newer card with more VRam but right now that is Not an option.
I also know DCS is Vram Hungry and guys with 24GB are choking but there has to be a reason the Vram is so high ingame? I am also running out of System RAM, the mission last night had me pegged @31GB RAM usage…
DCS is weird in that it reserves a LOT of VRAM. On my 1080 it took the full 8GB, on my RTX3080Ti it takes about 10 of the 12GB on the same settings as the 1080.
Someone did a test a few months back to see if more VRAM equals to better performance in DCS, in light of figuring out if a 3090 was the best card for DCS.
IIRC that person found that even though DCS ‘claims’ the VRAM it does not use very much of it. See it as a pipe and water;
DCS enlarges the diameter of the pipe, but the water volume through the pipe doesn’t change very much.
If you want to understand what is happening, the VRAM is a cache.
So it takes a relatively long time to fetch textures from disk (even SSD), so whenever DCS fetches some textures from the disk, it puts a copy in VRAM as well, so that it can access it faster when it needs it again.
It basically does this with everything, and so the cache gets bigger and bigger.
And about half the GB are probably filled with stuff it needs reasonably often, so not having to go to disk for that, makes the rendering faster, i.e. higher FPS. But that 8GB is probably also filled with stuff that DCS really doesn’t need that often. This has been shown by people testing DCS with different amounts of VRAM: there is seriously diminishing returns on having more VRAM. Even though technically, DCS uses it, it doesn’t help much compared to not using those extra GB and going to disk a few times.
What @Freak and others said. On my 1080 card, with 8MB, I would see an improvement in performance by lowering textures - I never ran it with any on a “high” setting. On that rig I had to compromise across the board in VR (It was worth it to me).
No way to tell exactly how ED manages the data on the GPU/VRAM but quick access to data will always be helpful…having as @Freak says, the data ‘close’ is related to capacity & access speed.
It probably uses a preemptive caching strategy, since a cache miss in such a quasi real-time constrained system is really bad, even more so for VRAM, because you first need to load an asset into RAM. The more space is available, the less intelligent the caching has to be in determining what will soon be needed but isn’t already available. Good preemptive caching is very complicated and I assume that ED have taken a rather pragmatic approach.
as you can see I am pretty much low settings. I turned up shadows and water but at 1 point I had it All on low settings. But I still get the over 8gb vRam usage it is really wierd… I am unsure what else to do here as I am trying to hold out for the 4xxx series vid cards at this point…
TL;DR: using VRAM is complicated. DCS always uses more than it needs. The more VRAM you have, the faster DCS is, but with dininishing returns.
To reduce VRAM load, turn down texture settings and render distance settings (scenery detail is also a render distance/LOD thing, especially important in Marianas ans Syria theaters)
If your only concern is a metric in a performance monitor, don’t bother. 8GB should be just fine with medium or high settings on 1080p. Set the settings to a level that works for you and don’t try to understand DCS’ VRAM usage, that stuff requires a computer science PhD
I am on Low and have tried setting everything to low. I posted a screenshot of my settings but I had turned up shadows for a test they seem to not much mind medium settings…
I just was wondering if maybe there was a lua file edit I could do to help lower vRam usage or similar… Guess I will hope for more vRam on future purchase…
EDIT: I guess I kinda miscalculated the amount of Vram I have I just checked and it said I have Global Memory Size 8192 MB
I keep forgetting about the 24… so I think I am good here and I just read where some guy has a 3090 with 24GB VRam and DCS choked that so I don’t feel so bad now I guess with DCS we will never have enough VRam if the guy with 24gb had issues with DCS using it all…