SLI / CrossFire FAQs

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There a few things that need to be cleaned up in the description if it's to remain a sticky.

You need to change the wording of the description of Xfire, you make it sound like ATi copied nV when if anything it's nV who copied ATi and Metabyte's methods of doing multi-card graphics. nV's SLi bears no resemblance to 3Dfx's SLI in anything other than name. And SLi didn't come first in the rebirth, that was Alienware's failed ALX and XGI's volari V8 Duo. And ATi was doing their SIMFusion thing the whole time with Evans & Sutherland.

Also you need to split the solutions up, since your first example of the same cards applies to SLi but not Xfire. So it should be clearly defined which one you're talking about, you examples lets someone guess, but it needs to be explicit.
And in the memory example following it, you talk about memory and then talk about speeds. The 7800GTX is a bad example for memroy since there is athat large difference. But when mentioning memory and talking about size you should mention the size being affected and that they will disable the added memory. You're sort of mixing your ideas here. Then right after that you say you can mix/mathc brands but make sure they have the same memroy and clocks, yet right before that you imply/state they can have different memory/clocks.
For an Xfire section you should add that while the cards need to be the same underlying architecture, they can have different numbers of shaders or pipelines and still work together, like an X1900GT + X1900CF combination.

Also when talking about multi GPU benefits, rememebr to mention that one of the areas of greatest impact is also in the minimum fps, where it will usually increase min fps and smooth out dips into the lower numbers. It's an important factor that's usually missed in the discussion and is the area that would be most noticeable to people not looking simply to push large resolutions or high settings.

And when talking about does it always improve performance, you should also mention that sometimes it actually hurts performance when using the additional card.

When talking about the memory doubling myth you may wish to expand on how the memory is used and why it doesn't 'double the memory' when in Crossfire/SLi mode.

When talking about 2 midrange beating 1 high end, the thing to rememebr is that there are exception to that, like 2 GF7800GTs beating 1 GF7800GTX-512 for less money, or 2 GF8800GTS beating a single GTX or Ultra for the same money, but it depends on the situation, because there's no clear cut rule for that.

I'd get rid of the 'which is better' comment, you could discuss that with intelligent people night and day and never get and answer, and posting to any one benchmark doesn't solve that question either. So I'd pretty much avoid it unless you take the time to explore it further than a link to a single group of tests.

Also I'd avoid posting a list of cards, unless you can keep it up to date and include all the sub cards, better to just link to AMD & nV's list thus the onus is on them and not you.

BTW, what the Crossfire/SLi RAMs sections? Sounds like you're talking about the 'certified' parts. But the way its written sounds like VRAM.

If you're mentioning 'Crossfire/SLi editions' etc. you might want to mention that for AMD the boxes stamped 'Crossfire Edition' come with the ribbon connectors required to run cards in Xfire.

There's also a few spelling mistakes, but I can clean those up directly if you want.
 
thanx for your suggestion , i really wanted to write something which isnt very hard to understand and is useful , but i am always opened to suggestions

Edited(BTW i will make uo my spelling mistakes too )
 

emp

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When I referred to midrange SLI vs single high end we refer to 7600GT SLI vs 7800GT(X), not 7800GT SLI vs 7800GTX. At least to me there is High end (Includes, but is not only top of the line), midrange, and low end/mainstream. To me the high end of a graphics card line would be for example ALL 6800 based cards of the Geforce 6 Series (Includes Vanilla, GT, Ultra, GS...), the midrange would be the 6600 series on all it's flavors (Vanilla, GT...), and the low end are 6200 cards, now this can all vary depending on how severely crippled a card is compared to the rest like midrange labeled car dangerously close to being a low end, as far as I know those might be isolated incidents like the 6600LE.

My point is, even if you get SLI 8800GTS over a single GTX you will most likely get better performance on some/most titles but it will not always be the case, however getting 8600GT on SLI to do the job of a 8800GTS will not get you anywhere near close the performance of the aforementioned. (Which is what I was referring on my first post)
 
Well the way I look at it is value/performance. My reply wasn't to what you said, just to the concept in general as the OP put it.

Regardless of what we give the 'label' mid-range, I'm talking about 2 cards at less than 1/2 the price. sometimes that's a GF7600/X1600, sometimes that's a GF7800GT/X1950Pro.

I think it matters less about the class than the concept, and that's where I think most people look anyways.
 

night_wolf_in

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about that two mid range cards vs high end card.

if i get to mid range cards work in crossfire, will it give me higher "min" FPS at resolutions 1600x1200 (maybe slightly higher, maybe lower). with high graphics settings?

why im asking, coz ill be buy 2600xt (which is good for budget). n i cant get 8800GTS, nor the new 8800GT (since it will be $200+). n probably in two/three month ill get another 2600xt.
 
2 midrange cards like 2 2600xt MAY beat a single 8800gts in lower resolutions (under 1600x1200) in some games, but in higher resolutions a single 8800gts beats 2 2600xt (it means a single high-end card will beat 2 midrange cards in most cases , but the difference shines in high resolutions)
 

night_wolf_in

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u got me confused there. lol. ill tell u what i understood.

1-two mid range can beat (or may beat) the 8800gts in lower resolution. in higher resolutoin the 8800gts will preveal.
2- but in high resolutions the two mid range will shine
 

Ironnads

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Lets take two 320 meg OC 8800gts cards in SLI (600$)
are they better than one 8800 gtx or ultra (at a higher price! - between 600 and 700$)
Actually I want to choose one or the other as I'm rigging a new box.
Iron Nads
 

emp

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Depending on the resolution and amount of AA the GTX might trump the two cards, because even though you have a lot of horsepower packing on those two cards you only have 320MB of VRam to play with, and that's not a lot.

On top of that you have A LOT more heat and power issues using SLI GTS OC over a single GTX, which in my eyes is not worth the hassle for maybe 5-10 fps more at lower resolutions.
 



i meant 2 midrange cards like 2600xt MAY beat a single 8800GTS in some games in low resolutions, but in higher resolutions , 2 2600xt dont stand a chance against a 8800GTS
 



exactly
thanx for helping me in this topic Emp :) ( u always have helped me :) )
 

emp

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NP :D By the way, have you tried Unreal Tournament 3 demo on that GTX of yours? Game looks awesome even at the max settings of the demo (Which I believe are not the max settings of the final game).
 



No unfortunately not , because when the download completed and when i clicked on it, it said Faild To initialize , and also because my Download speed is poor (16KB/S) it will take time to Download it again
 


Depends on the game and the settings. The problem with that example is that the GTS is both memory bandwidth and size limited, and so if you're playing a high-texture dependant game you're likely not oing to see anywhere near the performance, even if you do get an SLi boost. Which is the other issue some games don't get that boost.

however if there is a noticeable SLi boost inthe game you pick, and it is not memory limited, there's a good chance it will be competative for the price.

I still don't like a 2 card SLi solution versus a single card in general, but there are some cases where it makes sense, and in general those two cards usually keep their value better, as long as it's not 2 new cards against 1 older card, but 2 relatively similar generation card usually hold up better for selling as well.
 


Power levels definitely more. Not sure about the heat though now that nVidia has a more exhaust style blower HSF. It might actually improve your heat situation with more air being sucked out (and hence in the front) of the PC. The limited input of radiation and conduction likely isn't enough to make that much of a difference over a single card. I've seen more than a few say that their temps went down after adding a second GF8 or HD2K card, which is surprising until you think of the airflow effect.

Game looks awesome even at the max settings of the demo (Which I believe are not the max settings of the final game).

Yeah the demo is DX10, not sure about the texture quality though. I don't think it'd stress the GTS-320 beyond its limits in SLi, but who knows. Mark Rein talked alot about textures and DX10, so until the final edition comes it's hard to tell, and it could be a big shock for some people guaging their play on this demo.
I like it, but it's defintely less than they were promoting for looks. I don't care about the looks so much as if they have onslaught or not.
 

trek6500

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So then which would be better?

1.) 2 2900XT 512mb or 1GB in crossfire
or
2.) 1 8800XT or Ultra?

Aside from the extra noise and heat..

Good read Maziar! I am still trying to find a good overclocking MB, but the chipset choices are driving me bonkers in my decision making.
P35
X38
680I............................... :pt1cable:
 

trek6500

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Right, I understand the none multi gpu aspect. Isn't Multi GPU the way most games will go now?

Now are you saying that 2 2900XTs at 512 mb or the ones with 1gb of memory?

Also I wonder if there are any 20 to 24" LCD s with good enough refresh rates to really show off these cards at higher resolutions? Is it 6ms or less that you should be looking for?
 
if you read my post , there are still some games which wont benefit from MultiGPU also there are some games that benefit from MultiGPU, but they dont have siginificant difference with single card configuration (Due to some driver problems )

also again i have said this, MultiGPU really shines in high resolutions like 1920x1200 and higher

About the 2900XT question, well 2900XT 512 doesnt have much difference with 2900XT 1GB (if u want benchmarks , PM me and i will send you some)
 

trek6500

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Yeah man I read your post.. :kaola:
I was wondering about the memory difference. Like I read in one of your other post saying people need to remember that adding two cards together with 512 me doesnt mean you have 1gb of memory. So I wondered how 1gb would do compared to the 768mb Nvidia cards. Is it just overkill.
 
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