Nvidia SLI

I have a XFX gf 6800 and i got a motherboard that has dual pcie slots.
I should be able to put in a second 6800 and link them up in SLI. But i know there are mobo’s that have 1x(16Xpcie) + 1x(1Xpcie) and mobo’s that have 2x(8Xpcie). Many magazines state that it is best to go SLI with a mobo that has 2x(8Xpcie) as the loads between the cards will be more balanced.

I know that it sounds logic, but that doesn’t mean you can see the difference between a “balanced” SLI and an “unbalanced” SLI. Is there someone here that already seen the two setups? Does it make a noticable difference?


Seems SLI isn’t all that popular, seeing the answers here that is. lol :slight_smile:

they say that you are yet to see any difference with 8x and 4x PCI so 16 is overkill in my opinion. but also its a more logical option to go for two 8x than 1 16 and a half. I think sli is over rated right now, a single 7800 is good enough for me :wink:

Like i said, i haven’t seen any SLI in action, but i wouldn’t say it is overrated. I look at SLI as a cheaper way to get the graphics preformance up : you buy a second (cheaper then a 7800) 6800 and you can double the speed.

I also have a question about power consumtion when you run a SLI setup, as every GF needs 2 additional molex connectors for its power, they already recommend a powerfull powersupply, but in what order of watts should i think when i go SLI?

its cheaper if you already have a motherboard that supports sli, still if you just save up a little bit money you can get the newer 7 series card. Even though you have two cards you won’t get the 7 series features/ pixel shader 3.0 and other goodies. Power consumption is not only based on your vid cards, depends on what else you got going on.

not to seem annoying or anything… 6800’s have Pixel Shader 3.0.

And .soulty right there are a ton of features that the newer games use that you don’t see with the 6800 hardware (for example Oblivion uses some “special” graphical advances that arn’t seen with the 6800… i believe its somethign with the partical engine… which 360 had to omit completely lols).

2x6800 will be able to do more though becuase you will have the 512 of MB and you shouldnt see any lagg at all. (my friend at work has 2x7800GTX and he said it was so pointless to buy becuase his FPS is into the 200’s in all his games)

^ haha… yeah thats right the 6800 does, i was thinking the 6600. in any case ive run oblivion on my card and its so so sweet… hdr :drool:

hdr is great for single player, but in a multiplayer game, all the guys with inferior hardware have better vision. Now i keep getting pwnd by guys with 9600’s on dust:D

The 6800s don’t have native HDR support though. And some other goodies.

If you already have a 6800 and SLI it’s an okay way to boost your performance, but you won’t get nearly double. Not even half again as much. Look for about a 15% boost in performace with a second 6800.

wow 15%, you sure? that sucks.

get the 4 core new nVidia card, it is amazing, I own it i play quake 4 and on a 30 in screen i get 70 fps. It is insane

And i bet it makes your Ferarri look like crap

I remember it was something less than 25%. Either way, definitely not even half again as much. Mostly because games simply aren’t written to be streamlined for that, and the whole concept of rendering half a screen per card doesn’t work out quite as beautifully as it sounds, what with stuff crossing over and effects and stuff. In fact, I’ve heard HDR is pretty crappy with SLI sometimes because it doesn’t process together very well. It’s definitely not like having synergistic processors or anything.

i was just looking at a dual 512mb 7900gtx setup from dell… and dotn know much about this whole dual graphics card thing… do programs like maya take advantage of it? I wouldnt be running any games, so i dont care about what they do with them…

I thought programs like Maya love the nVidia Quattro and other graphics workstation cards…

As for rendering itself, I thought that was an entirely CPU option, so unless your work mode is slow, you don’t need it? Correct me if I’m being silly.

you can render with hardware now, which uses your graphics card but thats more quattro. Better to look into a dual core for better processing or using a rendering farm if your really going to go crazy.

:: in regards with viewing graphics or scenes in a 3d app your going to get enough from one powerful graphics card that will allow you to view major amounts of floating points, so dont think dual with get you much in those terms.

yeah, i mihg thave to look into the other workstation cards I guess… but they are soooooo expensive!

I Don’t need the sli setup for 3d apps, but for games… need is a big word, still running fine now…

I was surprised to read that a sli setup only gives 15-25% speed boost…

One GF 6800 gives 100% speed, an extra GF6800 would in theory boost you to a speed of 200% (double the speed). So a speedboost of 15-25% would mean that the extra GF would only give a 1/4 speedboost, and that sounds pretty low to me… Not saying that it is impossible…just surprising to hear…

Still i have the same 2 questions :
-Do you see a difference between a ballanced and unballanced SLI?
-If 1 GF6800 already has 2 extra molex connectors, and thus eats a lot of power, how powerfull does my powersupply needs to be to feed 2 GF6800?

an extra GF6800 would in theory boost you to a speed of 200% (double the speed).

Nah, I knew it wasn’t going to double the speed, but I didn’t know it was like 15%.