How much vram do I REALLY have?

I have a GeForce GTX 770.

According to the NVIDIA Control Panel’s System Information, it has 4 GB GDDR5 dedicated video memory.
According to DXGI_ADAPTER_DESC::DedicatedVideoMemory, it only has 3.93 GB vram.
According to the WMI query for the Win32_VideoController’s AdapterRAM, it has (4 GB - 1 MB).

…how much vram do I have, really?

Weekly bump.

I just rounded my vram to the nearest 512 MB, but if anyone has any insight I’d love to hear it.