This is misleading or a misunderstanding completely. The game code itself and libraries it use needs to load into memory, that's how programs run. Also, there's tons of memory usage outside of graphics, all the AI, calculations, basically everything happening in game requires some sorts of variable representing that's in memory. Bring up task manager and look at the memory usage of your programs and games. The game itself will be using multiple GBs, and the OS also use memory and keep some in reserve. Bad things happen when the system runs out of memory. The 16GB memory of the console will never be fully used by the GPU. In fact, the series X has a weird memory setup where 10GB has 560 GB/Sec bandwidth and the other 6GB has 336 GB/sec. That tells me the design is for 10GB reserved for graphics and 6GB for the game and OS. I'm not even sure if the full 10GB will be for graphics actually, some of the games take up a lot of memory and I'm not sure if 6GB will be enough for both the game and OS.As long as the PC has at least 16 GB of VRAM, and 16 GB of main ram, it will not need to prefetch any more then a console.