Q: to video addressing system

Hello. In a talk-back thread regarding some graphics cards tests some anonymous guy posted the following and corrected me.
Since he's anonymous I can't mail him and ask him more. But is he right? I would find it odd for the OS to present video memory space as system storage space for a game or other 3d accellerated application. I'd assume those new of the presense of the video memory directly, and would address that instead of system memory.

The source of the debate was, that someone claimed the amount of graphics card memory would impact the available memory in a 32bit system equipped with 4gb. ie. a card with 768mb memory might eat up more of the 3,2-4gb range than one with 256mb .... which in my world sounds silly. I was told, by otherwise literate people, that the amount of available memory is the result of various bios settings.


"When the OS loads the actual graphics drivers, it assigns a region of the address space to the graphics card. If there is enough unused address space, it gives it that, else it will overlap some of it with system RAM. This RAM is then mapped into an application's address space when taking advantage of hardware acceleration - so it can copy textures and write graphics commands - and hidden behind OpenGL and Direct3D."

The sound card is not what takes up the other ram alone, it is any hardware components in the system.

However, this is not my area as some people say that only a portion of the gfx memory size is reserved permanently in ram and it is swapped out a piece at a time. So instead of 512 being reserved it may be less but that as one portion is being written to, the space given up in the system ram is being replaced by what is being read back from the gpu ram if you get what i mean. The pci-e express should allow the simulatenous transfer.

No idea myself but some people should be able to explain the way it actually works.