iGPU virtual "VRAM" usage (as seen in Rivatuner OSD) can be seriously misleading. Quite often you're just looking at just the "window" itself (256MB buffer) rather than counting both the window + what's
through the window (256MB buffer + whatever more is being used in "non VRAM RAM" as an overflow but because of that never gets shown as "technically VRAM"). That's simply how Rivatuner often reports shared iGPU memory. A fixed 256MB "VRAM" size looks impressive, but doesn't really show what's happening. In cases like this, it's basically showing 256MB of RAM as "VRAM" and the other 768MB / 1792MB used in 1-2GB games eats into system RAM and appears as that rather than "VRAM". For example (8GB rig):-
- dGPU = In a game that used 2GB VRAM + 5GB system RAM used that would = 3GB of 8GB system RAM free.
- iGPU with forced 256MB VRAM buffer = It would show 256MB "VRAM" used + 6.75GB system RAM used = 1.0GB of 7.75GB system RAM free.
- iGPU with forced 1GB VRAM buffer = It would show 1GB "VRAM" used + 6GB system RAM used = 1.0GB of 7GB system RAM free.
- iGPU with forced 2GB VRAM buffer = It would show 2GB "VRAM" used + 5GB system RAM used = 1.0GB of 6GB system RAM free.
It's like putting a pagefile onto a RAM-Disk in an 8GB rig - whether you create a 4GB Pagefile on a 4GB RAM Disk leaving only 4GB System RAM, or just a 256MB pagefile leaving 7.75GB, in both cases, no matter what the figures say all you're ultimately doing is caching RAM into RAM. In the context of this thread, it doesn't mean that in an 8GB rig, a game which is using 2GB VRAM arranged into 256MB "VRAM" and 1.75GB "overflow" RAM will magically have 7.75GB free instead of 6GB free as actual system RAM available for programs that isn't being used for GFX, or even appearing to use "9.75GB" of 8GB RAM installed. The allocated vs actually used "VRAM" bit is just being misreported.