What exactly does SLI do?

SLi is basically a technology that allows you to split up the graphics rendering load over two nVidia cards instead of one.

This doesn't result in double the power, but there is a nice increase. So indirectly it allows you to run higher resolutions with better settings.
 
it's like hardware porn.. ;)

Seriously, it's like what iJeff says... adding: the management of the second card puts a decent load on the system, which is why you don't get "double the power" even though you have two identical video cards... also, one of the cards has to assemble the image before it goes to your monitor, so there's a little more management to do.. but with the way the drivers have matured, it's really come a long way in stability and performance...
 
Well, I havent tried this with one 7800GTX card, nor do I have any solid benchmarks, but......
I just fired up Riddick this weekend. Havent played it since Jan 2005 when I had a 6800 Ultra.
I ran the game at 16x12 with all the features and the game is insane. If youve ever seen it you'll know what I mean. I think it was/is one of the best looking games beside FarCry Ive ever played. It brought my 6800 to its knees.
I can ramp up HL2 Lost Coast and "see" all the benefits of HDR as can I in FarCry.

Basically, it takes two graphics cards and splits the workload. The master card them reassembles this image into what you see on the screen. Since you have two cards you can really ratchet up the settings and get butter smooth gameplay with some really fine,fine graphic quality.
I "see" things in my games that I was never able to see before.....in other words its very cool.
ATI has Crossfire, i have not seen a setup with that approach, but as the X1900XT can be put into Crossfire I bet its awesome as well. :D
 
magoo said:
ATI has Crossfire, i have not seen a setup with that approach, but as the X1900XT can be put into Crossfire I bet its awesome as well. :D
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magoo, you rock. who cares what kind of card you have as long as you're happy, and other people are happy? we need more of this kind of love in the forums.
 
To add to this as I haven't read anything current about performance, what are the gains up to now, roughly speaking? (nVidia in my case but I'll take links/info to either or both.)
 
It gives you some crazy error messages and helps develop some great troubleshooting skills. :p

nv4_disp.dll haunts me in my sleep. :(
 
Does it actually work? I mean do you really benefit by adding another card in SLI? By the time you spend money for another video card, a faster, single solution is released to the market. I am a bit confused.
 
Cannibal Corpse said:
Does it actually work? I mean do you really benefit by adding another card in SLI? By the time you spend money for another video card, a faster, single solution is released to the market. I am a bit confused.
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I think it works great. I had used ATi since the original radeon. This past christmas i decided to upgrade from a 9800XT. The 1800xt's were hard to find at the time, and about 600 bones. The x850xtpe's didnt support SM 3.0, and were two slot cards.

I decided to go with 2 7800GT's in SLI. Cost me about what a x1800xt cost at the time. Performance is great, and its pretty much as fast as one dual slot x1900xt. I run most of my games @ 1600x1200 with 60+FPS

BF2, UT2k4, Farcry, CS:S, Quake 4, COD 2....all in 1600x1200 and super smooth.

Thats all I could ask for.

If the new x1900xt had launched @ 450 bux and been single slot I would feel horrible, but it didnt.

So go SLI! ;)
 
Cannibal Corpse said:
Does it actually work? I mean do you really benefit by adding another card in SLI? By the time you spend money for another video card, a faster, single solution is released to the market. I am a bit confused.
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Oh Hell,yes. Believe me.....SLI is very cool. I had a single 7800GTX this summer. The X1800 series was not out. The single 7800GTX smoked my 6800 Ultra and essentially kicked the ass of TWO 6800 Us in SLI.....so I was happy. I came into some more cash dollars. I had to decide on what to do.....Crossfire wasnt available, I had a nForce SLI board.....so off I went to SLI land. You read my other post, no?? I think it was an excellent choice. Sure things change, sure now there are 512MB single cards and that X1900 looks sweet......but in September when I had the dough, adding another 7800GTX was the thing to do.....and I'll probably be good to go until the G80 cards arrive or maybe beyond. I like SLI because:1) it gives a good upgrade path,2)the image quality is insane,3)with my ASUS board it was cake to set up. Never a problem, not once. I have two BFG cards that kick ass.4)at the moment, my two 256MB cards can really keep up or may surpass any single card refresh, either the 7800GTX512 or the x18/1900s.
and the games are.....lovely :D (did I mention I liked it?)
 
If you like to game at high resolutions, SLI is really great... I have been a 1600x1200 gamer for a long time... and with SLI I can now enable all the eye candy while keeping the res up and it shreads through the frames... one thing I also noticed is that it really helps keep your minimum frame rate at a higher avg than with a single card, so there's a narrower gap between max and min (it stays closer to max :)). So even when tons of action is on the screen, it does not dip as sharply in fps as you are used to with single card play... I hope that makes sense.. anyways, thought that was an honorable mention.
 
Cannibal Corpse said:
What exactly does SLI do?
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SLi effectively allows Nvidia to take twice as much money off you then they could selling single card solutions and provides you with 3 months of pure speed advantage (far less then double the performance) over single cards until the next single card comes out that performs better then the last SLi but the good news is that new card will be available for SLi if you buy two and then you get the 3 months advantage again. Oh yeah and SLi allows you to turn off you’re second screen without using the power button! Bargin!
I’m sure Nvidia will realise that if they keep making single cards perform better then the last SLi that people will stop buying SLi so I expect they will make sure that doesn’t happen soon unless ATi is forcing them to boost the single card performance more then they would like to from strategic point of view.

The only reason I can think of that you would buy SLi for is if you have a game right now that you need to run at a very high resolution and you can’t wait for a single GPU to get the performance needed. It makes no sense as an upgrade option eg adding a second card later on down the track and it sure as hell doesn't make sense anything bellow high res.

Do you really think they are at the limit of what they can do with a single card? no
So the only reason to do it is to increase profits as they could get the same performance from a single card. It's a clever way to make more money simple as that.
 
Cannibal Corpse said:
Does it actually work? I mean do you really benefit by adding another card in SLI? By the time you spend money for another video card, a faster, single solution is released to the market. I am a bit confused.
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Although NVIDIA said it would appeal to those with one card, and be able to add another later, a large amount of people with dual gfx cards solutions just want the highest possible settings achievable

ATI was caught off-guard with how sucessful SLI was so now they have Crossfire, which is basically the same thing in theory(they work differently)
 
chinesepiratefood said:
ATI was caught off-guard with how sucessful SLI was
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I think Nvidia was also caught off-guard with how sucessful SLi was.

I can just see in my head an Nvidia meeting room with someone saying I think we could increase our profits buy people buying two of our top of the line GPU's the room goes quiet then they say that might just work but it would be only a very small amount of people who would pay for such a thing? Then a meeting later down the track I see the same person leaving the meeting in his new Porsche because his other car is on back order.. sniff sniff is that a cuban cigar I smell?
 
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