Why?![]()
Because Apple has, as always, limited it. If it was a PC, then I think you would be possible but as it's a Mac, it isn't. It's a "feature" in the driver and there is no nVidia tool for OS X anyway.
It's pretty useless anyway as the VRAM don't really speed up anything, maybe few FPS in games, that's all but it's better to leave the RAM for system, not for GPU
Only integrated GPUs actually use system RAM directly. Discrete GPUs use VRAM because it is faster than system memory. It can still use system memory to store textures when VRAM is full and ask the driver in the OS to fetch them, but it is slower than storing it in the GDDR3 memory.
This is automatic, and built into OpenGL and DirectX.
so are you saying it kinda does in a way?
i don't know very much about GPU's and VRAM.
thanks for all the replies so far =D much appreciated
Okay so then it's useless to buy the 512mb model then?
No, as the GPU has more space and will swap if necessary at a later time.