SLI / CrossFire FAQs

[Maziar]

Edited again, (Nvidi 3-way SLI, Hybrid CrossFire and some other things)

 

[TheForumMember]

Nice FAQ, very through.

 

[T8RR8R]

This thread needs to be on every forum out there. I have so many people asking me why they can't "SLI" two 3870's with a P35....wtf. Besides the fact that people are needing to use their own brains, more posts like this really help.

THANKS

 

[Maziar]

thakn you very much TheForumMember and T8RR8R

 

[wolfheart1979]

i bought 2 cards ati 3850 saphire and they are configured in crossfire.
i got a couple of problems which i would appreaciate if someone has the same problem and provides with any info :
1. after a couple of second in game call of duty 4 it crashes and when i try to open it agan it says DIRECTX ERROR ps. i am playing with ati 7.11 drivers.
My question is there any other configuration in CATALYST?

 

[Maziar]

mate you asked me with a PM and i will answer you there, so please don't post your question here too.

 

[ishbog]

Sooooo, I take it I can't use the old 7600GT my brother gave me (free ) with my 7800GT in SLI? Seeing as they are different models...

 

[nukemaster]

yeah, 7800 + 7600 = No SLI

 

[Maziar]

exact answer ^^
thanks nukemaster

 

[chron1]

I am glad I read this forum. What would you guys recomend for watching blue ray and playing games on a 50 inch plasma - two 3870 cards or an upcoming 9800 card?

 

[Maziar]

If the rumors are true and a 9800 is %30 faster than a 8800 ULTRA, then i would recommend 1 9800. but you have to wait and see what the exact specifications are.

 

[Maziar]

Edited

 

[chron1]

Thanks for the quick reply. I do not mind waiting. All I really want is to have the best possible picture quality for movies and occasional gaming.

 

[Maziar]

Edited (Added Nvidia Hybrid SLI )

 

[random1283]

im looking for a setup for 1280x1024 and was wondering about crossfire I have a ASUS P5K mobo

 

[Maziar]

Is it really necessary to use SLI or CrossFire ?
Well , it really depends mostly on the resolutions and games you play , resolutions like 1920x1200 and higher benefit more from SLI or CrossFire than resolutions like 1600x1200 or lower (I dont mean SLI or CrossFire wont be good for resolutions like 1600x1200 or lower , i am just saying that SLI or CrossFire shines in higher resolutions.)

So i dont recommend CrossFire for your resolution, also :

A note about Motherboards:
Some Motherboards support Multi-GPU Technology at Dual 16x mode, some support it at Dual 8x mode and some support it at 16x 4x mode, what are the differences?

Well for gettig the best performance out of Multi-GPU,you need a Motherboard that supports Multi-GPU at
dual 16x mode like Nvidia 780i SLI, NVIDIA 680i( As i said, NVIDIA 780I and 680i support 3-Way SLI too),Nvidia 590i SLI, Nvidia nForce4 SLI 16x, ATI CrossFire Xpress 3200 or Intel X38 chipsets.

Dual 8x is a very good configuration too,it doesnt have alot of difference with Dual 16x and its cheaper too.
Chipests like Nvidia 750i SLI, Nvidia 650i SLI,NVIDIA 570i SLI, NVIDIA nForce4 SLI, ATI Radeon Xpress 200, Intel 975x and ONLY 2 Intel P35 boards(ASUS BLITZ FORMULA and ASUS BLITZ EXTREME) support Multi-GPU at dual 8x mode.


The last one is 16x 4x, this one is the weakest and doesn't perform very good compared to dual 8x or dual 16x,so i won't recommend it for Multi-GPU configuration. Intel P35 and P965 chipsets support Multi-GPU at
16x 4x mode.

Dual 8x vs 16x 4x (ASUS P5B DELUXE vs P5W-DH DELUXE)
http://www.anandtech.com/video/showdoc.aspx?i=2837

 

[Farmer Brown]

Does anyone out there know if the spider platform can accomodate three cards? or are the options limited to 1,2 and 4.

 

[Maziar]

http://multicore.amd.com/us-en/AMD-Multi-Core/Quad-Core-Advantage/Spider.aspx

Scalable graphics you crave on your budget—up to four cards all running in
ATI CrossFireX™ mode, with support for up to eight monitors

Well i think when it says up to 4,then it can support 3 cards too.

 

[valorean]

Would using 2 cards that have more Stream Processors get more benefit from SLi and CrossFire than cards with lower Strream Processors? For instance say :

EVGA GeForce 8800 GT Video Card - 512MB DDR3, PCI Express 2.0, SLI Ready, (Dual Link) Dual DVI, HDTV, Video Card with 112 stream processors for 259.99
VS.
Visiontek Radeon HD 3870 Video Card - 512MB GDDR4, PCI Express 2.0, CrossFireX Ready, Dual DVI, HDTV, HDMI Support, Video Card with 320 stream processors for 249.99

I know it 2 different tech but its the only 2 cards i found in the same price range with a large difference in stream processors.

 

[yay]

"Warning: AMD/ATI cards need a CrossFire edition of its model to run at CrossFire mode (With the exception od AMD/ATI HD series)"

I believe "od" is suposed to be "of"

 

[Maziar]

to valorean:
the stream processors in 88xx series are different with the stream processors in HD 38xx or HD 29xx series.
As you see in the benchmarks,HD 3850/HD 3870/ 2900XT have
320 stream processors, and for example 8800GTX has 112 stream processors, and a 8800TGX (which has 112 stream processors) beats 2900XT (which has 320 stream processors)

Here is a useful link :
http://www.hothardware.com/articles/ATI_Radeon_HD_2900_XT__R600_Has_Arrived/?page=2

The 320 individual stream processing units in R600 are arranged in 4 groups of 80 SIMD arrays and each functional unit is arranged as a 5-way superscalar shader processor. In contrast, NVIDIA's G80 has up to 8 groups of 16 (128 total) fully generalized, fully decoupled, scalar, stream processors, but keep in mind the SPs in G80 run in a separate domain and can be clocked as high as 1.5GHz. In ATI's R600, each functional SP unit can handle 5 scalar floating point MAD instructions per clock. And one of the five shader processors (the fatter one in the image above) can also handle transcendentals as well. In each shader processor, there is also a branch execution unit that handles flow control and conditional operations and a number of general purpose registers to store input data, temporary values, and output data.

to yay:
yes,thanks i will edit it

 

[medjohnson77]

Thanks for the info posted on here, Emp has also gave me advice on my 8600GT that I thought about putting in SLI but I have decided to RMA it to newegg yesterday and will be getting new card or cards.

I am debating either a MSI 8600GTS Dimiond series in SLI, new egg has them for $138 dollars right now with a $20 dollar rebate, and one of the main reason's I am really considering these cards is that it has a HDMI output on it. With my $100.00 credit from my 8600GT that put the cost of the two at $280.00 - $40 on the rebate -$100 = $140.00 for the sli setup. Stream processors are only 32 on a single card and not sure how good this is. Ram is only 256 DDR3 clock is 700 i believe.

I am sure that emp if he responds will tell me to get the 8800GTX or ultra, but I am not wanting to spend over $300 at this time. If I can find a good 8800 series that can beat the MSI sli setup that is around $300 with out my $100 credit I think I can swing an extra $200.

Sorry for all the info but any advice would be helpful, cuz I am sending my card back today and will need to make a choice very soon, because my new custom build will be a paper wieght until I get the new card here.

 

[4745454b]

Your math is a bit off. Its $138 * 2 - $20 + shipping. Check the rebate info, only one per household/person. (Unless you are shipping one somewhere else, you'll only get one.) Not a big problem, but I thought I'd point that out.

8600GTS in SLI isn't enough to handle a 3850 AFAIK. The 3850 is pretty much the best sub $200 card out there right now. The 256MB 8800GT isn't a bad idea either. If I remember correctly, the 3850 and the 256MB 8800GT are pretty close, so I'd try to get either of these.

Last, not meaning to be rude, but I'm not sure the SLI sticky is the correct place to post this. Posting back to your old thread, or PMing someone would probably have been a better idea.

 

[Maziar]

Agreed, thank you 4745454b(i am glad to know your name, since typing your username takes a lot of time :d ) for your help,i appreciate it.

Also if you PM somebody,then talk about it in that PM,dont post it in this topic

 

[Maziar]

Edited