6850s crossfire 1gb is still only 1gb video ram right ?

[huntsman]

Hey guys I know that if I have 2 cards and they are 1gb each, my vram is still only 1gb. But I went on can your run it site and picked some games to see what the requirements are. At the end it says dedicated video ram and I would think it will only show 1gb but it shows 2.1gb why is that ? How does this read 2.1gb of vram and not 1gb?

Not like it matters but im just wondering how its getting 2.1gb.

 

[psirohi]

yes... unfortunately. Even if afterburner or your oc software tells you otherwise.

 

[Max1s]

Well its 1 GB per gpu, so it depends if the software is reading total VRAM (2gb) or gpu 0 vram (1gb)

 

[huntsman]

ah okay, wait so how come for games it only reads 1gb is there an article or something about this. Like why is it that it only sees 1gb instead of adding them together and having 2gb? Kinda interesting.

 

[Helltech]

It sees both of the cards. You do HAVE 2GB, the "games know" you have 2GB. The problem is that you have to load each card with the same information. Card one has to load all of the textures that card two does. In a sense you end up doubling the information you need, in which case you only have half (or 1GB) or effective memory.

Example, both GPU 1 and 2 must render the same scene. To do this they must both be given the same information, at the same time. So while there is 2GB of ram being used, its the same as having 1GB of ram.

 

[yumri]

what Helltech says is partially true it really depends on how you configured your crossfire setup though for the real answer. If you configured it for each card to render a entire frame then yes you only have 1GB of VRAM even though there is 2GB of physical VRAM but if you configured it so each card renders only 1/2 of the frame then it might be different depending on how the software using it.
In simple Helltech was right but when you get down to it it is more complex then just that.

 

[huntsman]

Ah I see so each card renders the same thing so how is it that 2 6850s vs 1 6850 are faster if each card renders the same scene why are 2 cards faster?

Where are the crossfire settings anyway ? I only have enable or disable.

 

[checkitman22]

what Helltech says is partially true it really depends on how you configured your crossfire setup though for the real answer. If you configured it for each card to render a entire frame then yes you only have 1GB of VRAM even though there is 2GB of physical VRAM but if you configured it so each card renders only 1/2 of the frame then it might be different depending on how the software using it.
In simple Helltech was right but when you get down to it it is more complex then just that.

thats not right, no matter what you do you always have effective memory of what ever the lowest memory card is (in case you CF a 2gb and a 1gb card together). the reason for this is just as helltech explained, both cards must load the same information at the same time. there is no situation or scenario where this does not happen