This is an interesting one. A user going by the name of Strife managed to install Crysis 3 on a GeForce RTX 3090, quite literally. By using half of the 24GB VRAM buffer on the fastest Ampere GPU as a virtual drive partition (VRAMDisk), he managed to install the game on the graphics card itself and run it directly from the VRAM.
The RTX 3090 comes with 24GB of GDDR6X memory. This guy partitioned it two sections, a 10GB and a 15GB variant, installing the game on the latter. So, basically, what he had was an RTX 3080 was Crysis installed on the on-board graphics card memory. Despite this, the total memory usage wasn’t maxed out, it topped at 20GB, with the GPU load at 40%.
This is likely due to the fact that the shaders had a much faster access to the textures and other game resources, resulting in no buffering and instant asset loading/swapping. This also reduced the latency, thereby, improving the GPU utilization.