Why only 896MB etc?

[Gothic Draconia]

Just a quick question.

Why do Nvidia use 320MB, 640MB, 896MB of memory for their cards whilst ATI use the traditional 256MB, 512MB, 1GB amounts?

 

[Richdog]

It's to do with bus-width. http://www.gpureview.com/memory-bus-type-article-378.html

However more is not always better, it depends on many other things in the design and implementation of the technology.

 

[Skyboat]

It's the size of the memory bus they use.

448bit (GTX 260) * 2 = 896Mb of VRAM etc.

 

[Gothic Draconia]

Thanks. I thought it was something along those lines but couldn't find anything confirming it.