AMD Smart Access Memory claims increased performance of up to 11% in some games. I am a bit new to graphics and am unsure where this increased performance comes from. The way I understand it is that uploading of data like vertex buffers, textures, etc to the GPU is usually done via a DMA staging buffer of some sort, whereas Smart Memory let's us access all of VRAM directly as opposed to 256MB chunks. Is the 11% boost just due to increased streaming speeds e.g. being able to edit part of a buffer resident in VRAM as opposed to resending the entire thing over the PCI connection with a staging buffer? Sorry if this made little sense, I am not the most knowledgeable on GPU architecture.
I guess fundamentally the question is where does the CPU benefit in having more than 256MB of directly addressable VRAM, because atm the only thing i can think of is if you want a dynamic vertex buffer or something along those lines.