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2 times Geforce 7950GX2 to drive 4 monitors

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July 28, 2006 11:58:25 PM

I have been reading and reading all about SLI but still didn't find a straight answer. Maybe you guys can help me out.

I am about to start a software project OpenGL based for which I need to specify the hardware. I need to power 4 displays simultaneously from a single PC. I am planning to have a Pc build with a Intel core 2 Due E6700 and two 7950GX2 cards inside.

I understand that quad SLI is not yet supported and that is fine but will such a configuration work to power four displays via the 2 x 2 DVI outputs?

What I did find, is this old article from 2004 http://www.tomshardware.com/2004/11/23/nvidia/page31.ht... which suggest this should be possible today.

What are your thoughts on this. Feel free to email me:

vandinther@gmail.com
July 29, 2006 12:08:00 AM

pretty sure u cant run 2 monitors in SLi. because of the way the cards render the scene. if u get SLi u can have more than one out put while the cards are running in SLi. u can get a splitter from matrox tho which should solve some of your problems.


http://www.matrox.com/mga/offhome/dh2go/home.cfm

here we go. or just buy a really fuuck off big screen.
July 29, 2006 12:16:51 AM

You can run four monitors from two videocards
Related resources
July 29, 2006 12:23:15 AM

Quote:
You can run four monitors from two videocards

yes but not when they are working in SLi. so you would be fine in desktops but when the card is told to work in SLi it only uses one output. i think it has something to do with the way the screen is rendered. AFR and all that lark.
July 29, 2006 12:27:13 AM

Thanks, but OK. four GPU's four screens. I don't need to have them running in SLI as long as all four GPU's are actually doing work. So how would that work? One GPU per screen?
July 29, 2006 12:35:42 AM

im not sure you can. to get the second GPU running when u have two cards you need to enable SLi. its not running by defualt and when it is running it needs to be told what to do. so in principal the same theory works for 4 GPUs aswell.
u would have all four GPUs working on the same screen.

you cant seperate them and treat them as seperate GPUs. they work together to create a single DVi output. not four.

so if u did connect four screens you would only be using one GPU. which would kill your frame rates...

why do u need 4 screens BTW???

And no, hopeful gamers, you can't use four monitors in SLI mode. Any game that can be bludgeoned into working on multiple screens will work as you'd expect it to with two 6600s or 6800s, based on the graphics cards' basic specs. But most of your gaming, and all of your SLI gaming, will be single-screen only.
July 29, 2006 12:38:00 AM

I understand it is openGL but do all 4 or only 2 monitors have to be 3D. If 2 will be 2D then you can use a 7300GS for the 2D work and it is faster in 2D than the higher cards are in 2D I benched the 7300's, 7600's, 7800's.

If you need 4 in 3D then get a motherboard that has PCI-X slots such as the TYAN S2895. This AMD Opteron will give you more flexibility. Get some nice fast Matrox cards to do the 2D on the PCI-X bus and keep the OpenGL on the PCI-Express bus. You can even have a fast raid controller to speed up you disk access on the PCI-X bus. With this board you need 2 cpu's to run both PCI-Express slots.

Another choice but Intel based would be the ASUS - P5WDG2-WS down side is that when 2 x16 PCI-Express video cards are installed they become x8
July 29, 2006 12:39:54 AM

I'm with Dougie, hard to explain, though.

You do NOT want SLi as that combines the GPUs. What you want is a motherboard with four PCI-e x16 slots...

I might be wrong, slightly confused.

~Ibrahim~
July 29, 2006 1:30:48 AM

This configuration is not for a game but a software project I am about to embark on. This thing is a simulator of some kind which needs 4 3D displays

I understand the SLI issue. If I don't use SLI then the second GPU on the 7950GX2 won't be utilised.

So basically I want 4 graphics cards each driving their own monitor.

Is there such thing as a 4 x PCIe 16X mobo?
July 29, 2006 1:48:21 AM

lets ask google...



*2 min*

computer says no.

how much power would you need???
because there is an old martox card which CAN run 4 monitors...
July 29, 2006 2:17:28 AM

To run 4 monitors you should only need 2 video cards with 2 outputs each. You would probably not want to put them into SLI, any 2 cards should work fine.

The way it should work is as follows:

You install both cards SEPERATELY (i.e. not in Crossfire\SLI), Windows should recognize two discrete cards with 2 outputs each, then you plug in all four monitors Windows should see 4 monitors, you kick back and enjoy.

That being said I've never seen someone actually running a setup like that. What I have seen though is a guy who hooked 9 computers to 17 monitors and had them all running one copy of Microsoft Flight Simulator.

So to recap, any mobo with 2 PCI-e 16x slots, any two video cards with 2 outputs should work. Good Luck.
July 29, 2006 2:47:50 AM

Quote:
What I have seen though is a guy who hooked 9 computers to 17 monitors and had them all running one copy of Microsoft Flight Simulator.


jesus fu.cking christ. how... where... what sort of frame rate was he getting???
July 29, 2006 3:46:11 AM

Quote:
What I have seen though is a guy who hooked 9 computers to 17 monitors and had them all running one copy of Microsoft Flight Simulator.


jesus fu.cking christ. how... where... what sort of frame rate was he getting???

How: a third-party program written for Flight Simulator designed specifically to allow multiple computers to run MSFS together (like a cluster)

Where: Maximum PC, Rig of the Month section (if I find the specific issue I'll post it)

Frame Rates: I assume playable since the whole point was a more realistic playing experience

EDIT: September 2003 issue
CORRECTION: 13 monitors (still impressive though)
July 29, 2006 5:05:39 AM

Indeed, no need for a SLI gfx card setup (SLI is only for single-monitor setups), but you do want two slots (for whatever gfx cards you want to use) on the mobo (this might mean a "SLI" mobo, even though you aren't going to use it in that fashion, but it will have 2x8 lane or 2x16 lane PCIe slots).

Wow, that was a long sentance, I hope you understood.

Don't get the 7950's! Those cards aren't what you need (unless you need some SERIOUS horesepower running each seperate monitor). I'm guessing that each GPU on the 7950 would power a single monitor in a 4-way setup.

Be sure that the cards have 2 outputs each. Have you checked into the Quadro line from nVidia, or FireGL line from ATI. I'm not sure what you're gonna be using these for, but those are the workstation cards from both companies. It will depend on what you will be using them for as to what you need.
July 29, 2006 5:30:33 AM

Quote:
Be sure that the cards have 2 outputs each. Have you checked into the Quadro line from nVidia, or FireGL line from ATI. I'm not sure what you're gonna be using these for, but those are the workstation cards from both companies. It will depend on what you will be using them for as to what you need.


Quadro and FireGL cards are designed for 3drendering and CAD applications, while they usually have decent speed for gaming and the like they tend to worry more about accuracy of rendering than speed. Additionally they usually lag behind more commercial cards in their driver development because the drivers are subjected to much greater testing than the commercial drivers.
July 29, 2006 4:32:49 PM

@Fred

He MUST get four cards because then one card would be running two of his OpenGL things. Yes, it would work, but the card would have to work twice as hard to do two different tasks at the same time.

The Gigabyte mobo should work and just a note: No need for two threads.

~Ibrahim~
July 29, 2006 5:14:41 PM

Get 7900GTXs instead and run two displays on each card; you can't do what you're asking with quad SLI.
July 29, 2006 6:35:32 PM

try checking these links:
G450x4 MMS
or
QID Pro

the latter one is an OPENGL card... this is the right one for your project. :D 
July 29, 2006 8:33:44 PM

@Strange

That might be possible...It might be more expensive to have two computers, though?

@rvnarvarro

I think you have the perfect solution. It actually has four chips, one for each output. Only question: Is it strong enough? I mean, it is running thru PCI.

~Ibrahim~
July 29, 2006 10:35:12 PM

That Matrox solution seems to be for 2D applications only. This seems to be the way for more than 2 displays. All those solutions are 2D and don't provide specs for 3D performance.

Multiple PC's is not a good option due to the programs reliance on physics simulation which can not be exactly reproduced on multiple PC's thus resulting in mismatching views.

This is an answer I got from NVidia:

I asked:

Quote:
In relation to answer ID 58 I have a further question. I want to buy two geforce 7950GX2 cards to drive 4 separate displays. The answer to Question ID 58 tells me this is possible but are all 4 GPU's involved in the graphics rendering? And if so, does this mean that each GPU drives one display?


They answered:

Quote:
The Geforce 7950 GX2 is a multi GPU graphics card which has two GPUs working simultaneously. Each Geforce 7950 GX2 graphics card supports dual displays. Therefore, two such cards will support four displays. However, each GPU does not support one display.


Let's limit the scope to one 7950GX2 card. Would you say that both GPU's power the two outputs? since such a card is essentially one graphics card with an internal SLI bridge?

So extending on that, simply adding a second 7950GX2 would simply add another two outputs powered by it's own SLI configuration.

So it becomes 2 x 2 SLI and not quad SLI?

The head spins, how are they going to sell this to the public. Maybe I should just get two 7900GFX cards and be done with it.

(By the way, sorry for the double post. I'll stick to this thread now)

It still doesn't conclusivly tell me that it uses both GPU's for the
July 29, 2006 11:29:00 PM

If I can span the picture INGAME to both my monitors at a total resolution of 4096x1536, I'm sure you can span four monitors wide for ridiculous resolutions ingame... Won't be fast though, don't expect 60fps in pretty much any game.
July 29, 2006 11:41:08 PM

Quote:
@Fred
He MUST get four cards because then one card would be running two of his OpenGL things.


Not neccesarily, it depends on what he's trying to do. If he is doing high-end graphics then 4 cards may be worthwhile. On the other hand if he simply needs 4 monitors then 2 cards is enough (or even just the one with 4 outputs). A 7900GTX for instance has a LOT of power, if he is doing even mid-range graphical stuff 2 of them would probably be more than enough. In the end he should probably try 2 cards first before he buys non-mainstream hardware.
July 30, 2006 12:24:03 AM

Exactly. But if he needs a GPU to each monitor, that must require heavy power, no?

~Ibrahim~
July 30, 2006 5:03:48 AM

I think I am trying to be too close to the cutting edge. Maybe I should consider 2 x 7900GFX and be done with it. I am in total control of the graphics content and rendering complexity so I can tone it down to suit the available hardware if needed.

Bottom line is, I want the best possible graphics hardware solution available today to drive 4 monitors in 3D.

I hear the suggestions about stretching graphics across 4 monitors but I am not sure if I understand that. I need 4 different views on the same scene which are not nessesarily all aligned with each other. The software I am writing basically will provide 4 separate view windows where each window can be placed on a particular monitor.
July 30, 2006 6:33:01 AM

Mate! the Gigabyte GA-8N SLI QUAD ROYAL Motherboard appears to be the solution. I love it! I read this review from Toms hardware http://www.tomshardware.com/2005/10/04/one_gigabyte_mot...

The mobo can power up to 8 displays via the 4 card slots and even more is you add some PCI cards. This is ideal because inaddition to the 4 view displays I might want to power a few more screens for periferal use. Instruments, rearview mirrors and instructor station.

I have the feeling this board can do this. What I am not sure about is if this board can host the new Intel Core 2 Duo E6700 processor which is the one I would like to get.

Anyway the Mobo tip from you was very good. Thanks for that
July 30, 2006 1:25:30 PM

How many mice are you gonna use? :p 
You'll have to skid that mouse pointer all over the place XD
July 30, 2006 4:15:26 PM

Quote:
Bottom line is, I want the best possible graphics hardware solution available today to drive 4 monitors in 3D.


Then you should get the motherboard with 4 PCI-e slots and pick up high-end cards for each 7900GT-7900GTX or ATI equivalent. Don't bother with the 7950, I don't know if multiple SLI's in one machine would work right and 4 of them would jack the price WAY up.
July 30, 2006 9:27:43 PM

Yeah, it is a really good motherboard. The FSB supports Core 2 Duo which is a major part, but there are some voltage changes that might be needed. I looked in the BIOS updates, they mention something about CPU microcode or something. I'd ask with Gigabyte to make sure.. If you can get a Core 2 Duo, that thing will be blazing!

Yeah, 4 7950GX2's might need another mortage, lol...

~Ibrahim~
July 31, 2006 3:42:02 PM

Curses! I checked the Motherboard CPU Support list, here, and they list that the Core 2 Duo did not work with their test. Damn, that would've been perfect, then..

Next month, nVidia is opening the 590 SLi to Core 2 Duo, but I haven't heard anything about any more Quad PCI-e x16 slots on a motherboard, though the Intel 590 SLi is capable of four PCI-e x16 slots. Sorry.

~Ibrahim~
!