lopri
Elite Member
- Jul 27, 2002
- 13,221
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This is something I've been curious about. The relationship between frame buffer vs bandwidth. This question arose from my experience of HD 3850 (256MB) and 8800 GT SLI (512MB each).
It's important to note that there just aren't many games that fills up 512MB of memory by design in a given frame. We've seen something similar to this from the Asassin's Creed debacle. For instance, under DX10.1, apparently some of the frame buffers can be re-used for post-processing (which still have to be filled in the memory), thus AMD cards benefited from it. Say, in a hypothetical situation:
- Card A (512MB): constantly (quickly) moves or reuses 300MB of buffer efficiently thanks to extremely high bandwidth and smart design
- Card B (1GB): slow to switch frame buffers or constantly redraws same buffers again and again (brute force)
Of course there is a case where absolute amount of memory is needed (such as Qual's texture mod). If ONE frame needs more than 500MB of physical RAM to be drawn, then 512MB card will suffer badly. In this case the 1GB is necessary. But my experience, as well as what others say, is that NV card has a problem with memory management. Especially in newer titles and DX10 titles.
Whether this is a hardware issue or drivers issue isn't still clear to me. For instance, ForceWare 175 improved alot in this regard compared to ForceWare 169 in my experience.
Anyway, I'm planning to get a 4870 (512MB or 1GB, whichever I find first) so I will make sure to test it out on my 30" and let you guys know.
It's important to note that there just aren't many games that fills up 512MB of memory by design in a given frame. We've seen something similar to this from the Asassin's Creed debacle. For instance, under DX10.1, apparently some of the frame buffers can be re-used for post-processing (which still have to be filled in the memory), thus AMD cards benefited from it. Say, in a hypothetical situation:
- Card A (512MB): constantly (quickly) moves or reuses 300MB of buffer efficiently thanks to extremely high bandwidth and smart design
- Card B (1GB): slow to switch frame buffers or constantly redraws same buffers again and again (brute force)
Of course there is a case where absolute amount of memory is needed (such as Qual's texture mod). If ONE frame needs more than 500MB of physical RAM to be drawn, then 512MB card will suffer badly. In this case the 1GB is necessary. But my experience, as well as what others say, is that NV card has a problem with memory management. Especially in newer titles and DX10 titles.
Whether this is a hardware issue or drivers issue isn't still clear to me. For instance, ForceWare 175 improved alot in this regard compared to ForceWare 169 in my experience.
Anyway, I'm planning to get a 4870 (512MB or 1GB, whichever I find first) so I will make sure to test it out on my 30" and let you guys know.