I have two recent notebook computers with XP Pro, each with the NVIDIA Quadro FX Go 1000 GPU with 128MB AGP memory. They both have the same NVIDIA 60.85 driver installed.
I noticed some OpenGL based features are performing vastly differently on the two. I wrote a program that opens some OpenGL double buffered windows and uses DirectDraw to report available video memory at various points in the program.
Both computers show 119MB AGP memory available when the program starts prior to opening an OpenGL window. After opening four OpenGL double buffered windows, one notebook reports >80MB AGP available while the other reports only 14MB AGP available.
What could be causing the large difference in these otherwise identical systems?
My only thought would be that the AGP aperture setting in your BIOS is set differently - one might be set at 128MB and the other at 256MB which basically allows system memory (makes up the difference) to be used for texture and display lists.
Out of curiosity what are you using to determine the AGP memory usage?
The result (when it nears a low number) seems to be consistent with the time when hardware accelleration performance drops considerably (from 30+ fps to 2 fps).