VRAM Usage - 6970 (2 GB) vs. GTX 580 (1,5 GB) vs. GTX 580 (3 GB)

[adonys]

that's exactly what i've asked on the other thread too: we really need someone with a single GPU card with 1.5/2/3 GB VRAM do an AIDA test on IL2 CoD on variou graphics settings.

[Buchon]

There a lot of confusion in this thread about how SLI/Crossfire work.

SLI/Crossfire cards and systems dont share VRAM between GPUs.

So the effective VRAM of a dual GPU with 2 GB is what is assigned to a one GPU.

That mean that in a dual GPU card with 2 GB of VRAM there a 1 GB of effective VRAM becouse, in fact this card are two single cards of 1 GB VRAM.

[adonys]

Originally Posted by Buchon

There a lot of confusion in this thread about how SLI/Crossfire work.

SLI/Crossfire cards and systems dont share VRAM between GPUs.

So the effective VRAM of a dual GPU with 2 GB is what is assigned to a one GPU.

That mean that in a dual GPU card with 2 GB of VRAM there a 1 GB of effective VRAM becouse, in fact this card are two single cards of 1 GB VRAM.

I was saying that DUAL GPU (590 GTX & 6990) cards might have their VRAM shared. We need to check the vendor's specifications for that.

[Armatian]

No mem is shared, is duplicated, dual gpu cards are the same like one gpu card with crossfire/sli conection inside the card.

[Kankkis]

Originally Posted by Armatian

No mem is shared, is duplicated, dual gpu cards are the same like one gpu card with crossfire/sli conection inside the card.

True, that's the reason why my game is sturrering like hell, i got 5970 2gb but really it uses only 1gb, there is people who's getting allmost smooth gameplay with over 1gb.

Weird thing is that even i play all setting about min, i got stuttering and my hd loading, how the hell game can use so much vram even low detail?

Kankkis

[louisv]

SLI stands for Scan Line Interleaving...

Simply put if you have two cards in sli, one card does the top part of the screen and the other does the rest. Logically this means that the two memories must have ALL the information in each.

Double cards are a compact SLI package, that is all.

Louis

[adonys]

yes, but that doesn't mean they can't have both GPU accessing the whole memory (as the memory is on the same card, the accesing speed should be faster than accessing the other GPU's memory via a SLI link).

is highly improbable, but as none of us really knows the way the hardware of dual GPU works, we can't have a say in this.

that's why I said we need to dig this up.

[madrebel]

Originally Posted by louisv

SLI stands for Scan Line Interleaving...

no this is what sli used to stand for. sli now = scalable link interface.

[Codex]

Originally Posted by Buchon

There a lot of confusion in this thread about how SLI/Crossfire work.

SLI/Crossfire cards and systems dont share VRAM between GPUs.

That's not entirely true. It depends on how the developer has set up the buffers in DirectX. While yes they physically don't share memory, but with DirectX you can map the memory to appear as one huge chunk.

http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx

[madrebel]

Originally Posted by Codex

That's not entirely true. It depends on how the developer has set up the buffers in DirectX. While yes they physically don't share memory, but with DirectX you can map the memory to appear as one huge chunk.

http://msdn.microsoft.com/en-us/libr...=vs.85%29.aspx

no, you can't. each GPU has X memory. gpu1 can't access gpu2's memory. if GPU2 even wanted to access GPU1's buffer then this would slow down the frame draw process which is why it isn't done.