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per nvidia, 2 9800gx2, 2 monitors, non-sli not supported

Last response: in Graphics & Displays
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June 24, 2008 12:16:15 PM

Hi,
I recently purchased the following system:

Operating System: Windows Vista Home Premium 64 Bit
Motherboard: EVGA 132-CK-NF78-A1 NF780I SLI
CPU: Q9450 2.66G overclocked to 3.2 gHz.
Memory: 8 gig OCZ OCZ2RPR10664GK
Video Cards: Two (2) MSI N9800GX2-M2D1G GF9800GX2
Hard Drives: Three WD 640GB 6400AAKS SATA 7200RPM 16MB. Two are in raid 0, with the OS installed on the raid array.
CPU cooler: XIGMATEK HDT-S1283
DVD Burner: LITE ON LH-20A1L-05 20x superallwrite SATA+lightscribe
Power Supply: ENERMAX EGX850EWL galaxy
Case: LIAN LI PC-P80B

My idea was to run one 24” monitor from the top PCIE slot and another from the bottom. I did not want to do quad SLI. Monitor resolutions are 1920x1200.

I spent about a week attempting to do this. I tried every way I could imagine to get this to work, and couldn’t. I could accomplish the following:

1. Get one 9800gx2 working in multi-gpu mode. 3dmark vantage score of about 10500.
2. Get one 9800gx2 working in multi-monitor mode. 3dmark vantage score of about 5500.
3. Get two 9800 gx2s working in quad-sli. 3dmark vantage score of about 15000.
4. Get two 9800 gx2s working in multi-monitor mode. 3d mark vantage score of about 5500.

It’s obvious from the above that:
1. A 9800gx2 with both halves of the card working together is about 10500.
2. A 9800 gx2 with only one half of the card working is about 5500.

I can’t get each card outputting to an individual monitor with each card performing in mult-gpu mode. I contacted nvidia support, and their answer is summarized here:

“I'm sorry but you cannot run two separate instances of Multi-GPU mode with two 9800GX2 cards. You can only disable SLI and be able to operate in a multi display environment or enable Quad SLI and be limited to a single display. What your trying to configure is not expected behavior nor supported.”

Ok, so nvidia doesn’t support what I’m trying to do. I won’t debate here whether I think that’s reasonable. So that leaves me with one super fast quad sli machine, or one dog of a multi-display system. I’d love for that to be somewhere in the middle.

Has anyone figured out a work around to help me accomplish what I want to do?
Is it possible to modify nvidia’s drivers to allow this?
Has anyone gotten the work around trick of adding a third cheap video card to work with 2 9800gx2s in quad sli?
Would the Matrox doubleheadtogo work for what I want to do?

I appreciate your time in reading this post, and look forward to some constructive replies.
a b Î Nvidia
a b C Monitor
July 8, 2008 1:51:47 PM

Don't think a third video card would be supported on your mobo as its not on my xfx nforce 790i, Check with evga support and ask them if its possible.
The problem here is that even tho you have 2 graphics cards, your system is actually recognising 4 because of them each being dual GPU.
I doubt that putting a third card in the ageing pci slot would even work.
I havent got a second monitor to try it out for you :( 
July 17, 2008 10:33:24 AM

hmm, I have been looking for an answer to this as well..


I have the same problem as you with a slight twist :

I have a triple monitor setup via triple head 2 go and i also have a quad sli setup (I know, its overkill as my triplehead2go will not produce the resolution required of a quad sli setup, but I had these cards before I went the 3 display route - use to use a 30 inch monitor which leads me to my next problem - trust me, gaming in a three monitor setup is way better - for me at least).

I also have a 30 inch monitor just sitting in my closet that I've been wanting to use for a 4 display setup. I was thinking since my mobo has an extra pci-e slot, could I get a another PCI-E card and use that for my 4th display?

So, aarong you are not alone in this matter....I can't believe nvidia would give you such an answer

Any help would be appreciated.

Thanks
July 17, 2008 11:03:04 AM

What I ended up doing was RMA'ing the second 9800gx2. I bought an overclocked 9600 gt oc. Now i have the 9800gx2, running in multi-gpu mode and the 9600 gt powering my other 2 monitors. It works really well.

A longer discussion on the topic can be found at http://forums.nvidia.com/index.php?showtopic=70681&st=0.

The guide you'll need to get a 9800gx2 and 9600 gt working right together is at
http://www.overclock.net/nvidia-drivers-overclocking-so...

As to making a 3rd video card work with quad sli, I don't know. If you have one laying around, give it a shot. I'd believe the biggest problem for me if i'd gone that route would have been heat.

Keep us posted.
!