Does SLI increase vram usage?

JVictorSR · Nov 4, 2013

Does SLI increase vram usage. Would 2 770s use more vram than one? Thanks!

PepitoTV · Nov 4, 2013

Nope, they actually get restricted to the lowest vram card, ie if you SLI a 4GB 770 and a 2GB 770, they'll use only 2GB of VRAM.

JVictorSR · Nov 4, 2013

Actually, if I have 2 770s in sli, would they use more vram then only one 770 not in sli?

bystander · Nov 4, 2013

VRAM usage will not change. CPU usage will increase slightly, to handle some SLI/CF overhead.

JVictorSR · Nov 4, 2013

bystander :

So 2 770s will use the same amount of vram as one 770?

bystander · Nov 4, 2013

JVictorSR :

Each GPU will use the same amount of VRAM as a single GPU on its own. This is because in SLI or Crossfire, each GPU still renders a full frame on its own. Each card will handle every other frame. This means both cards must use their VRAM exactly the same as a single GPU configuration.

Example:
Single 770 may use 1.5Gb in a game.
In SLI, each 770 will use 1.5Gb in the same game.

JVictorSR · Nov 4, 2013

bystander :

JVictorSR :

Each GPU will use the same amount of VRAM as a single GPU on its own. This is because in SLI or Crossfire, each GPU still renders a full frame on its own. Each card will handle every other frame. This means both cards must use their VRAM exactly the same as a single GPU configuration.

I mean like if one 770 uses 1.5 gbs of vram in some game, then 2 770s will use 1.5 gbs of vram too?

HugoStiglitz · Nov 4, 2013

yes that is correct, it does not stack (does not function like raid for your VRAM)

JVictorSR · Nov 4, 2013

Sorry, I mean like if one 770 has 2 gbs of vram and uses 1.5 gbs of in one game, then 2 770s will use 1.5 gbs of 2gbs of vram too?

bystander · Nov 4, 2013

JVictorSR :

Each of them will use 1.5Gb of vram (it is not 1.5Gb shared).

JVictorSR · Nov 4, 2013

Sorry, youre not understanding the question. If I have 2 gbs of vram, and I utilize 1 gb of it in a game, then will 2 770s utilize more of the 2gb than the one 770, right?

bystander · Nov 4, 2013

JVictorSR :

You are not understanding our answers.

Imagine the same game in two different scenarios.
Single GPU mode:
770 uses 1.5Gb

2-way SLI:
770 (1) uses 1.5Gb
770 (2) uses 1.5Gb

3-way SLI:
770 (1) uses 1.5Gb
770 (2) uses 1.5Gb
770 (3) uses 1.5Gb

4-way SLI:
770 (1) uses 1.5Gb
770 (2) uses 1.5Gb
770 (3) uses 1.5Gb
770 (4) uses 1.5Gb

HugoStiglitz · Nov 4, 2013

No, the usage of VRAM is directly related to the game settings (Resolution, AA & AF & ETC) it has nothing to do with how many cards you have or the fact you have a 1, 2, 3 or 4gb card

if the settings your using demand 1.5gb of vram and you have 1gb card then it will max your card.
if you have a 2, 3 or 4gb card then it will just use the 1.5 it requires.

hunter315 · Nov 4, 2013

You're just asking the same question over and over, if you don't get the answer you like the first two times its time to rephrase and form a more detailed question.

In SLI each card must store all of the data it needs to work with, and must store its rendered frame prior to transmission. If card A when running by itself is using 1.5GB of 2GB of VRAM in a specific game, then you add a second card B and keep the game at the same settings, card A will be using 1.5GB of VRAM its own still, card B will also be using 1.5GB of its own VRAM. Most of the data on the cards will be the same, they both need to have the textures they are dealing with loaded into their VRAM.

In short, SLI/CF does not increase the effective available VRAM, it only increases computational power.

JVictorSR · Nov 4, 2013

Thank you all very much. Sorry for being an annoying noob. Forgive?

Tohst · Nov 29, 2013

Everyone is saying that VRAM does not stack, and that each card in SLI will use the same amount of VRAM as the other(s).

Then what is the point of SLI? What does it do? If you are going to be running Skyrim with 50+ mods on a 1440p screen, would it be better to have 2 2GB cards in SLI or one 4GB card? What's the difference?

It seems to me like SLI and more VRAM in a single card accomplish the same thing - they allow more pixels to be rendered more quickly.

bystander · Nov 29, 2013

Tohst :

VRAM does not speed up rendering one bit. VRAM is a storage container for the GPU. It only effects rendering speed if you don't have enough. You either have enough or you don't, there is no in between. So in the vast majority of the time, a 2GB card is the same as a 4GB card.

SLI increases speed by allowing two video cards to split the load of rendering frames. They do this by having each card render different frames. They still render an entire frame by themselves, so it does not change the amount of VRAM needed and they do not share their VRAM, but every other frame is rendered by a different card, allowing both cards to be actively creating different frames. When everything works perfectly, SLI doubles the speed, but there are usually losses in performance due to the extra CPU load, which now has to feed 2 GPU's at double its normal pace.

Whether or not SLI is better than 4Gb of vram depends on whether you have enough vram. If you are running short on vram, and you are seeing your FPS drop badly as a direct result, then double VRAM will likely help more than SLI. This is extremely rare, but having 50+ mods in Skyrim is one case where that can happen. It even happens with 4gb cards, and 6Gb cards. This means with Skyrim, you have to control yourself and not install every mod available.

Does SLI increase vram usage?

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