Per Nvidia, 2 9800gx2, 2 monitors, non-sli not supported

Discussion in 'Videocards - NVIDIA GeForce' started by agoddard, Jun 24, 2008.

  1. agoddard

    agoddard New Member

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    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.
  2. WinMacLin

    WinMacLin Member Guru

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    GTX 1080 Ti
    The Double Head 2 Go would work for what you want, but you must realise it doesn't give you 'Dual View' where you have two separate desktop environments like you do when you use Multiple Monitors on a GPU without SLI enabled.

    Instead the Double Head 2 Go puts to two displays together in to one very large display. If you launch a game in fullscreen mode it will consume both displays at once, instead of just 1 display like Dual View.

    When in SLI mode you cannot run Multiple displays unfortunately.. It's one of those major annoyances with SLI that NVIDIA have yet to remedy. (Which btw ATi have fixed with their multi-GPU implementation).

    If NVIDIA is watching, I think they should create a fast-switching function in to there Drivers for enabling and disabling SLI in the same way that Vista enables and disables the Aero Glass effects when a Game is launched / closed. And then make that function automatically activate and deactivate SLI mode as 3D games are full-screened.

    Either that or enable Multi-Monitor mode while in SLI which would be preferred...

    About using a cheap 3rd card for driving extra Monitors. I believe that 'trick' works on most cards as-long as you use a card from a different series to the one your using. For instance a 7 series card. I'd suggest waiting before obtaining one of those until someone confirms my suspicion though as I don't know for sure.
  3. El Bastardo

    El Bastardo Member

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    I can feel what you feel

    Yeah I know NVIDIA can be "such a bitch".

    What I want to accomplish is even more "freakier" but really nothing special (just out of the ordinary).

    I have a (one) 9800 GX2 and the card has three outputs and two chips. So even four outputs should be possibly (ATi has it with there 3870s).
    But anyway three are fine because I have two monitors and one TV.
    So both DVI outputs in my monitors via DVI<->HDMI cables and one HDMI cable to my TV (HDMI<->HDMI).

    My scenarios: Either run both monitors to work (TV os off) or just run one monitor (to play with SLI) or run the TV in the evening to watch (and one or both monitors are off).

    The good news: It's possible (somehow) BUT what a pain:

    Every time you have to consider so much things and switch so much.
    SLI on/off DualView is crapped up every time you switch, resolution and refresh change because the monitors are 1920 x 1200 and the TV is 1920 x 1080 and so on.

    NVIDIA PLEASE do something with your drivers. They can control so much why not some essential things like fast SLI switching and profile saving. Your cards do have three connections and there are people that want to USE THEM and not just think I COULD!!

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