The physical video memory capacity is displayed incorrectly in Windows Vista and in Windows Server 2008 if the graphics adapter’s physical video memory is at least 4 GB
A Windows Vista-based or Windows Server 2008-based computer uses a graphics adapter that has at least 4 gigabytes (GB) of physical video memory. After you start the computer, the physical video memory capacity is displayed correctly on the screen during the Power-On Self Test (POST) stage. However, after you log on to the system, the system incorrectly reports the physical video memory capacity.
This incorrect information appears in different user interfaces. For example, when you view the adapter information in the Display Settings item in Control Panel for a graphics adapter that has 4 GB of physical video memory, the Dedicated Video Memory section shows only 0 megabytes (MB).
For more information on this issue, including potential causes, workarounds, and resolutions, see: Microsoft KB Article KB958360.