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What exactly does SLI/Crossfire do.

Emjay86

Emjay86

Emjay86

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Hey guys,

Silly question but what exactly does SLI/Crossfire do?

Im aware that it bridges two of the same graphics cards together but how do you measure the power of that combination?

For example I have 2 580 GTX cards linked. What difference will that have in comparison to a single 580?
 
How well it's supported will determine what level of scaling you'll get. One game might run well on SLI but not so well with Crossfire, and visa versa.
 
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- Run Game in SLI/CF, determine avg FPS
- Disable SLI/CF, repeat step 1
- ???
- Profit

In all seriousness it's fairly game dependent but SLI/CF support is almost always available on any major title these days, indie games may not see it but most of them don't need that power anyways.

Typical perf gains is around 80-90%, so we're nearly at the magical 2x performance. Results can vary depending on the rest of your spec however.
 
It is very CPU dependant thats why most people who have xfire and sli go for Intel i7 CPUs and these days the most recent gpus i.e. And 7900 series can run all new games at full detail how ever with multi screen and 3d setups it is better to have atleast 2 gpus to cope with the extra load.
 
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It depends on the Algorithm used, but one example would be that one card draws the top half of the scene, the other card the bottom half, then it sends it over via the SLI bridge to the first card where its pieced together and sent to your monitor :o

Another algorithm that could be used is that one card draws one frame, and one card draws the either. Which ever Algorithm is used it results in up-to twice the performance (but not always).

But dont listen to me im a total noob :p
 
I mainly ask as I was trying out the Battlefield 4 beta and I noticed that the Geforce experience software optimised the graphics to display textures as low and it got me worrying that ill need to upgrade my 2 580s.

Reason why I worry is I only just finished waterblocking them and it will be a great waste of cash if thats the case!

It could have course be down to it being beta.
 
2x580's are just a bit faster than a 680. if they are the 1.5GB versions, it could be because of the lack of vram. I would turn the settings to max and see what you think of the smoothness.
 
Emjay86 said:
I mainly ask as I was trying out the Battlefield 4 beta and I noticed that the Geforce experience software optimised the graphics to display textures as low and it got me worrying that ill need to upgrade my 2 580s.

Reason why I worry is I only just finished waterblocking them and it will be a great waste of cash if thats the case!

It could have course be down to it being beta.
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The Beta is taxing even high end systems, ive seen 690 (Dual GPU) owners complain of sub-par frame rates and my GTX780 barley kept 60FPS untill I overclocked the hell out of it so I wouldnt worry untill the official release :cool:
 
The beta is not optimised at all so don't worry till the officail release.

I would wait till the officail release to make a decision on if this game is playable or not.
 
mattacuk said:
The Beta is taxing even high end systems, ive seen 690 (Dual GPU) owners complain of sub-par frame rates and my GTX780 barley kept 60FPS untill I overclocked the hell out of it so I wouldnt worry untill the official release :cool:
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My FPS are fine its just the GeForce experience put my graphics down on its optimise option. Without that I still noticed no real issues with performance it just looked really nice.

That said my watercooling loop was running at 45 degrees today and yesterday it was 55 (got me worried about reaching the 60 max for the tubing!). Im still only using 1 360 rad for my 2 gpus and cpu however as im waiting for my rad to get plugged in (waiting for payday basically).

Im hoping to get another 1-2 years out of the two cards I have before I get the next 'big' thing.
 
Emjay86 said:
That said my watercooling loop was running at 45 degrees today and yesterday it was 55 (got me worried about reaching the 60 max for the tubing!).
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what tubing are you using? ive never heard of anybody worry about their tubing getting too hot - unless yours is made of chocolate or something? :p
 
panyan said:
what tubing are you using? ive never heard of anybody worry about their tubing getting too hot - unless yours is made of chocolate or something? :p
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Its XSPC and it says the max tempt is 60c so naturally I worry whenever it gets anywhere within 60c
 
Indeed never heard of a tubing max as when I get mine to fit over the pump I normally put it in really hot water to get it to fit and I have never had a problem.
 
swiftmetal said:
Indeed never heard of a tubing max as when I get mine to fit over the pump I normally put it in really hot water to get it to fit and I have never had a problem.
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lol thats actually a good point, I did put mine in hot water prior to fitting them on the compressions...

Oh well it says 60c max so it makes me uneasy of going near 60.
 
Surely that's just the CPU/GPU hitting that temp (which is fine, the coolant will be much lower), if it was the coolant I'd be worried :p
 
Erm its my GPU. I don't have a temp log for my coolant or my CPU atm.

I need to find a program to display my GPU and CPU temps on my Logitech G19, currently it just shows my 2 GPU's.
 
SLI and xFire these days gives almost double performance. The scaling has really come a long way since it's release.

Once you hit three or four GPU's though, the scaling isn't as good. Two is the sweet spot imo.
 
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