kilcondlost

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Now I know you all probably think this is stupid, but I am very curious. I am looking at building a new x79 set up using the MSI Big Bang XPower II as the motherboard and the i7 3930x as the processor. I am in to bit coin mining and right now run my setup with 1x5970 and 1x5950 at 1200 mhash/s. The big bang comes with 7 Pcie slots 16x/1x/8x/1x/8x/1x/8x/1x

I know there are motherboards out there with all the slots at at least 4x and I know power is an issue I know the heat would be immense and there would have to be a LC set up to make everything fit, but I am really only looking for an answer to the fundamental question. If all of the other criteria is met can you run 7x7990s out of crossfire at the same time?

Also similar question can there be some of the graphics cards in a computer linked by crossfires/sli and the rest not be linked (i.e. 2 x 7970s in crossfire and 2 x 7970s not linked) or would the computer just take them all out of crossfire before allowing you to do anything?

Just so you know I have spent a good amount of time researching this and I have come up with answers that seem like they should answer my question, but are not definitive. I don't want you to think that I don't know how to use google. Your answers would be much appreciated as I really don't want to drop 5 grand on a computer that doesn't work 100%

Thank you, Russell
 
G

Guest

Guest
You wouldn't have the space, a 7990 would take two pci-e slots. You could 4 way crossfire(which is actually 8 way) although I would be worried about the heat considering how much the 6990 put out.

Does bitcoining work? how much do you make if you don't mind me asking.

 
From a 'CF' (CrossFire) standpoint you are limited to 4 GPU processors (Quad-GPU), and since the HD 7970 has 1 GPU processor then the limit is 4-WAY CF HD 7970's. The same Quad-GPU pertains to both SLI & CF, this is a driver limit and there's no way around it currently.

Other than that, Folding, Rendering or (GPGPU) isn't limited it quite the same way. There are PCIe chassis for this purpose, and most of them are CUDA and Tesla use.

Example - http://www.dell.com/us/enterprise/p/poweredge-c410x/pd?refid=poweredge-c410x&isredir=true
 

fil1p

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Hey,

No, you cannot do this for a few reasons:
First and most importantly BOTH AMD and Nvidia only support up to 4way sli, crossfire. Now the 7990 will be a dual GPU card most likely, that means there are two GPU's on one card, meaning you can only run up to two of those cards in crossfire to get 4way CF. You could run 4 Hd7970 is CF, as they are single gpu cards and you can have up yo four of them.

Besides that driver support for quad GPU set ups is not too good, and there is no such thing as 7 card support, so that would not work.

Besides those two reasons that make it almost impossible, you would have to run them at x16 or x8 speeds, and they would have trouble fitting in your case, unless you have 14 free slots (each card is dual slot). Another problem would be the heat, yes you could run it in an LC set-up, but in the first place you wouldn't be able to as 7 cards are not supported in crossfire.

i have once heard of someone who ran 4 GTX590's in SLI, although that required a lot of modding to achieve.

Hope this helps!
 

venur

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Just to add my two cents. 4x 7970 > 2x 7990 (both solution are a 4way crossfire).

Also 4x CF/sli get a minimal gain from 3x CF/sli. On a usefull scale even if possible going for more then 4x CF/sli would be useless just for the power needed. Just a 3x 7970 require a 1200w PSU and would probably be able to run every game at max graphic quality and 4AA till 2x CF of the next generation of GPU will become an upgrade.
 

kilcondlost

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Alot of you seem to be stuck on Crossfire, now just so you know you do not have to have cards set up in crossfire. You can have 2 cards not linked by crossfire in your computer. So as I stated in the OP I know that there is a limit to 4way SLI/Crossfire but for bitcoining that does not matter.
Now Thently that is interesting I did not know that. Why is that the case? I thought that you would end up losing about 30% capacity but I didn't know that you could't run them at all. Please let me know because that could be a killer.
As ahnilated said I can fit 7 in my set up as it with watercooling the fan is removed and that is the part of the card that makes it take up two spots. The waterblocks are only a few mm thick and can easily fit in a single slot. Heat would still be an issue but I would be using a 480mm radiator for 4 and a 360mm radiator for 3 of the cards.
As for drivers since each card would be working individually as long as the driver works for one it should work for the others too. They don't have to communicate so I wouldn't see what the problem is.
Ivan with the setup I have now I make about $5 a day after power costs. I know not much but its do to my limited set up as I only have the 3 PCI slots with no WC. If I was to do this setup and make it work it would be producing between $35-$50 a day but would cost $5600+ for the gpus $400 for the MB $600 for the cpu and dual power supplys at $250 each as well as the Azza 4000 case (so I can fit it all) at $250 total... $7100. My plan is to buy the main setup and one card and then allow the earnings to buy the rest of the gpus. It roughly takes 2 months to pay for each gpu to pay for itself. I would have 1 and then 2 months have 2 then 2 more months have 4 and so on.

 

rubix_1011

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Running multiple video cards does not automatically mean you are running Crossfire or SLI...this has to be enabled in the driver. If you are running separate cards for GPU processing, this isn't reliant upon Crossfire/SLI...just on the physical GPUs being present and recognized by the system and driver.

In fact, people running GPU processing would likely NOT have either of these technologies enabled since it wouldn't benefit them and any overhead associated with those drivers could either cause reliability issues while running these processes or add to actual processing overhead.