There is no “cause” to the out of VRAM problem as this even happens on blank projects, Blank as in the ‘Blank Template’ from the ‘New Project Menu’.
This can even happen on 3090s and 4090s which have 24!GB of VRAM. The root cause is the engine itself. Epic needs to have a look at this as this is not what is called PRODUCTION READY, it’s hard to be PRODUCTIVE if the engine keeps crashing within minutes. There are still bugs that date back to the earlier UE4 days.
Another good indicator that it is nothing related to assets or hardware is that all of the crashes stop immediatley if you switch the RHI to Vulkan (which still uses Nanite and Lumen) but the problem there is that performance is generally cut in half in most scenes because Epic is unable to implement it properly.
Epic just needs to stop putting useless new ■■■■ into the engine and start fixing whats already there. The Early Access period of this engine is officially long over and even then, the Early Access version was WAY more stable than all versions after it upto the most recent 5.1.1.
They just very shoddily implemented the different render api’s and thats whats causing the problem. And at the very least, the engine should be able to detect the available VRAM and limit everything accordingly as does almost every game on the market.
For a recent example and to stay in the same engine, Hogwarts Legacy, if i set the Textures to the MAX and on top of that ENABLE RAYTRACING at 4k, i’m around 4gb OVER my available VRAM but does the game crash? No, not even after a multiple hour long play session, yeah it start’s to run like crap in certain places because of the constant swapping between system memory and vram, but does it crash? No not a single time! And this is how it should behave and that game uses a modifed version of UE4.
Even when disabling all of the fancy new mostly non-working features the engine keeps constantly running out of VRAM whereas the same scenes worked just fine in UE4. To top it all of, i even tried importing the same exact Megascans with 8K textures into UE4, no problems at all, in UE5 immediate ‘Out of VRAM’ errors even with the same base settings (Nanite, Lumen, Virtual Textures disabled to match UE4’s default settings).
Over the last couple of months i’ve sent them around 4GB worth of logs and crash reports and i have yet to see any response to that. They just don’t care!