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Does 7970 CrossfireX Share VRAM ?

post #1 of 4
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In BF3 it uses 4.7GB of VRAM
Source: http://hardocp.com/article/2012/03/28/nvidia_kepler_geforce_gtx_680_sli_video_card_review/5
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post #2 of 4
No, the monitoring software is showing total allocated memory for all GPUs so you have to divide that number with the number of gpus you are using... CF mirrors the data just like SLI
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post #3 of 4
i tried my best to google something for you but can't find it.

AMD's Crossfire does work differently from SLI. It has alternate frame rendering mode, which is what SLI uses i think but also other ones like checkering, which basically divides the whole screen to a checker board and the videocards render each one differently and split screen rendering, which divides the screen in half and both videocards render their halves.

Alternate frame render would not "share vram" which is why SLI can't, unless Nvidia made some improvements with the big bang driver that I am not aware of and the other modes crossfire supports might be able to share vram, but i'm not 100% sure.

However, when the drivers see an unrecognized application, they default to alternate frame rendering to be more compatible. However this is what gives Nvidia an edge when games are first released, since most of the games are optimized for alternate frame rendering with "Nvidia meant to be played" branding. After a few weeks of drivers optimization though, the AMD driver team figures out the best configuration and best modes to use.
post #4 of 4
Quote:
Originally Posted by Grobinov View Post

No, the monitoring software is showing total allocated memory for all GPUs so you have to divide that number with the number of gpus you are using... CF mirrors the data just like SLI

This.

It doesn't matter how many cards you have, the VRAM is mirrored and not added together. The monitoring software for CFX just shows you the total VRAM you have or are using upon X amount of cards.
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