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8800GT SLI + VRAM Question

Last response: in Graphics & Displays
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May 13, 2008 10:36:47 PM

Okay, from what I understand, Gcards in SLI do not share VRAM. So, here is my question. I have a 8800GT 512mb card. If I were to buy a 8800GT 1Gig card, could I then make that my main card and add the 512mb one in in SLI setup to work as the extra GPU?

The theory goes as such if I did not explain myself well. I want to buy a 1gig 8800GT so that I have extra vram headroom for running games such as crysis and Age of Conan in all the glory. I was hoping I could SLI my old 8800GT 512mb as the dependant card with the 8800GT being the one whos VRAM is being utilized.

Thank you.
a c 176 U Graphics card
May 13, 2008 10:55:47 PM

If I understand you correctly, it doesn't work that way. When you SLI cards, they have to "match". As soon as you pair that 1GB card up with a 512MB card, half of the memory will be used so that they "match". Its kinda like setting up an AID0 array with two different sized harddrives. As soon as you hook up the smaller device, the larger one downsizes to match it.

When using SLI, both cards use their own Vram. What you have is 2x512GB, not 1x1GB.
May 13, 2008 10:58:11 PM

4745454b said:
If I understand you correctly, it doesn't work that way. When you SLI cards, they have to "match". As soon as you pair that 1GB card up with a 512MB card, half of the memory will be used so that they "match". Its kinda like setting up an AID0 array with two different sized harddrives. As soon as you hook up the smaller device, the larger one downsizes to match it.

When using SLI, both cards use their own Vram. What you have is 2x512GB, not 1x1GB.

Yep, the 512mb card will run of of vram first, and reach across the bus to use main system ram, which will lag it down. I suppose it's still better than both cards trying to access main system memory, but basically, you won't get the main benefit of 1gb onboard ram.
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a b U Graphics card
May 14, 2008 1:54:12 AM

logically speaking it makes sense... but as far as I understand sli just makes it possible to have 2 or more cores working on something... still limited to the max overall vram on one of the cards though
May 14, 2008 4:48:26 PM

So, it will simply read both of the cards as running at 512 megs of ram then?

Drat, I was hoping I could install the 1gig by itself, then install the 512 afterwards with the 1gig taking the Vram focus.

I was told in another post that They do not share Vram, but what one of you replied with is that it sees it as 2x512meg, implying that they would both write to their own individual vram.

The way it was explained to me is that the first card would be the primary. It would have data sent to it for computation and store information in its vram, and that if I added an SLI card, the second one would simply act as a secondary GPU feeding information back to the system.

Yes/No?
a c 176 U Graphics card
May 14, 2008 8:00:47 PM

I'll assume you mean this post.

Quote:
The 1 gig one would be perfect for SLI since sli doesnt share vid memory,putting 2 normal 512 mb ones doesnt equal a gig.


This basically says what I said. If you have two 1GB cards, you'll finally have 1GB of Vram. If you SLI two 512MB cards, you don't have 1GB of Vram, but 2x512MB. (which is what I said earlier.)

Quote:
Drat, I was hoping I could install the 1gig by itself, then install the 512 afterwards with the 1gig taking the [-b]Vram focus.
[/b]

I have no idea what that means.

Quote:
I was told in another post that They do not share Vram, but what one of you replied with is that it sees it as 2x512meg, implying that they would both write to their own individual vram.


This is correct. Its not a shared resource like with RAM.
May 15, 2008 6:06:32 PM

Okay, still not getting it. What I am asking is this. If I got a 8800GT with 1gig of ram, and then ANOTHER SEPARATE card with 512mb, could I install the 1gig card one first, and would it uses ALL 1gig of the VRAM seeing as how they don't share Vram.

Basically, buy a 1gig 8800GT, slap a 512 GT into SLI with it, and gain the benefit of the 1gig from the first card.
a c 176 U Graphics card
May 15, 2008 7:37:39 PM

4745454b said:
If I understand you correctly, it doesn't work that way. When you SLI cards, they have to "match". As soon as you pair that 1GB card up with a 512MB card, half of the memory will be used so that they "match". Its kinda like setting up an AID0 array with two different sized harddrives. As soon as you hook up the smaller device, the larger one downsizes to match it.

When using SLI, both cards use their own Vram. What you have is 2x512GB, not 1x1GB.

!