You quoted the statement that apply to limitations of DXGI budget monitoring API. It doesn't allow you to peek outside the scope of process you're running inside. D3DKMT (used by ProcessExplorer, new GPU monitoring capale task manager, GPU-Z, HwInfo, MSI AB etc) does that and allows each process to peek inside other process GPU usage (per-node) / VRAM usage statistics etc. D3DKMT VRAM usage related fields (introduced in Vista times) were 32-bit. Probably the developer who created them thought that 4GB (limit of 32-bit value) of VRAM will be enough for a long time They changed to 64-bit representation with W8 only.