Multi-monitor SLI Users Rejoice!

Hey guess what? If you've got SLI and two monitors, you no longer have to turn SLI off to use both monitors. It's been 4.5 years since the introduction of SLI and we finally have support for a feature that should've been there from the start. Granted AMD/ATI/SnowWhite didn't have support for this multi-GPU/multi-monitor setup until last year with the Radeon HD 3870 X2 so it's not purely a NVIDIA thing. If you run a full screen 3D application your second display will go blank and come back as soon as you've quit your application, whereas in the past you had to go into the NVIDIA Control Panel, enable SLI, run your 3D app/game, go back in, disable SLI and then you'd get your second display back. In the new driver you don't have to do any of this - sweet.

While NVIDIA's driver supports up to 6 monitors, for SLI to work you can only have displays connected to the master card in SLI with a maximum of two monitors connected. So if you want to have more than 2 monitors and support SLI you'll either need three cards or you will still need to disable SLI to get your non-master SLI card to output video.

The multi-monitor driver interface also got an update in a very sensible way; you can now select which monitor will receive the display when running in SLI mode, it's no longer tied to a fixed output on your video card. Hooray for flexibility!

While selecting the SLI Focus Display is done in the SLI settings menu, when adjusting your multi-monitor setup, there is an indicator that lets you know which display is the SLI focus display. It's a little green square in the corner. Check it out.

When we played around with it, the primary display had to be the SLI Focus Display when the primary display was connected to the SLI bits. The only way to make the primary display (the one with the start menu and all that stuff) not the SLI Focus Display was to run it off a second card. At which point, the SLI Focus Display could still be selected if two monitors are connected to the SLI hardware.

Another multi-monitor feature to note is that 3 games (Flight Simulator X, World in Conflict and Supreme Commander) are also accelerated across multiple monitors. We would really like to see all games supported across multiple monitors (without the use of one of Matrox's DualHead2Go or TripleHead2Go boxes), but there are still some difficulties with rendering a game across multiple displays when the game does not expect to have its framebuffer split. It is good to see that NVIDIA is at least extending support of new features in new drivers to games whose developers have specifically included multiple monitor support.

The extensiveness of the SLI and mulit-monitor flexibility is nice, and we are definitely glad to finally have all of this working. It's been a long time in coming, but we are glad that it's finally here.

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  • Finally - Friday, November 21, 2008 - link

    Thank you Derek for your insightful posting, clarity and all.
    The only lesson I can extract from your writing is the common man's knowledge that you shouldn't mess around with SLI/Crossfire, ever.

    [quote]As a 3870X2 quadfire and 4870 Crossfire owner I can say without doubt that AMD driver support is lousy and bordering on scandalous... I still do not have a Crossfire profile for Fallout 3 and it has been almost a month."[/quote]

    Stop bitching. You called for your personal grief and you got it delivered alright. If you got too much time on your hands and want to spend them on ridiculous hobbies, so be it - but don't bitch for the common man.
  • Finally - Friday, November 21, 2008 - link

    To clarify the meaning of "calling for personal grief":
    Putting too many graphics cards in your rig is like hiring a motorcycle gang to beat you up with sticks and chains and all and then running around the town, showing your bruises and bloodpouring to everyone complaining how bad you are feeling after that paid-for encounter...
  • tejas84 - Thursday, November 20, 2008 - link

    Derek Wilson is 100% right. As a 3870X2 quadfire and 4870 Crossfire owner I can say without doubt that AMD driver support is lousy and bordering on scandalous... I still do not have a Crossfire profile for Fallout 3 and it has been almost a month.

    I had to wait for TWO catalyst revisions until Crysis Warhead and Stalker CS had profiles as well as GRID, Assassins Creed, World in Conflict etc etc....

    Nvidia put the effort to work with developers to ensure the games work with their hardware and integrate SLI profiles. AMD are arrogant and I remember an AMD moderator say that the TWIMTBP program was simply paying for a logo. For a company betting everything on multi GPU isnt it strange that AMD doesnt work with devs to get Crossfire profiles into game.

    Well actually they pay so that their games work well with the latest games. AMD are lazy and cut corners just like with their CPUs and frankly I am going to sell up my AMD cards and go exclusively Nvidia from now on...

    Bottom line... anyone who thinks that Derek is being harsh has NEVER OWNED AN ATI CROSSFIRE SETUP BEFORE....


  • Griswold - Friday, November 21, 2008 - link

    Point and case why multi-GPU solution suck donkey nuts, no matter what team you depend on - you depend on them twice as much as everyone else (one for the raw driver and its bugs or lack thereof and one for the profiles). No thanks to that.

    Tough luck, I say. And with nvidia on, what seems to be a financial downward slope, it remains to be seen if they're willing and capable to deliver in the future. Good luck, I say.
  • Goty - Thursday, November 20, 2008 - link

    So wait, I think you're forgetting the whole "Call of Juarez" deal. ATI had a deal with the developer there in the same manner that NVIDIA has a deal with all the developers that participate in the TWIMTBP program. NVIDIA's hardware performed like crap in the game when it was first released and everyone cried foul, saying that it was "unfair" and "anti-competitive" for AMD to do something like that.

    Now, if we want to talk about anti-competitive, what about NVIDIA's dubious dealings with Ubisoft and Assassin's Creed and DirectX 10.1 support? Hmmm...
  • tejas84 - Thursday, November 20, 2008 - link


    Well actually they pay so that their games work well with the latest games- this refers to Nvidia
  • chizow - Thursday, November 20, 2008 - link

    Its not the first, Anand recently ripped into ATI drivers in his Core i7 launch review:


    We have often had trouble with AMD drivers, especially when looking at CrossFire performance. The method that AMD uses to maintain and test their drivers necessitates eliminating some games from testing for extended periods of time. This can sometimes result in games that used to work well with AMD hardware or scale well with CrossFire to stop performing up to par or to stop scaling as well as they should.

    The consistent fix, unfortunately, has been for review sites to randomly stumble upon these problems. We usually see resolutions very quickly to issues like this, but that doesn't change the fact that it shouldn't happen in the first place.

    Its a problem that has been gaining momentum lately and has drawn a LOT of attention with the recent Farcry 2 driver debacle. First there was the issue of render errors, hitching in DX10 and overall poor performance without FPS caps. Then there were hot fixes, fixes for hot fixes and further hot fixes. Then there were CF problems with newer drivers that necessitated using drivers that had the render errors or DX10 stuttering or both. But it comes down to this, if the recommended fix for a problem is to revert to prior drivers, its pretty clear the monthly WHQL program isn't working.

    ATI gets more heat because their drivers tend to be more reactive than Nvidia, who tends to be more proactive with their TWIMTBP program and driver updates that come in advance or arrive in tandem with hot launch titles. This latest round of reviews and performance in top 5 titles would confirm this.

    ATI has also made multi-GPU their solution for high-end performance, which means their products rely heavily CF scaling and compatibility. A big problem here is that ATI does not have user-defined profiles for games like Nvidia, which means there is no recourse if you have poor CF scaling or performance short of workarounds like renaming game .exes.
  • giantpandaman2 - Thursday, November 20, 2008 - link

    Where's the blame on Ubisoft Montreal? Can't a game company release a game that works with a large portion of video cards?

    That said, I think AMD should go to once every other month. Less overhead, more things fixed with the same amount of man hours. nVidia drivers simply take too damn long. They go to the opposite extreme if you ask me. I owned an 8800GT and it took them 9 months to get their video card fully compatible with my monitor in Vista64. That's ridiculous.

    But, seriously, why do people only blame driver makers and not the fricken game makers who have easy access to the hardware?
  • DerekWilson - Thursday, November 20, 2008 - link

    game developers are hitting a moving target as well. they don't have the drivers that will be out when their game launches until their game launches ... and it would have been final for month(s) before that.

    in contrast, AMD and NVIDIA can get their hands on those games months before hand and make sure that drivers work they way they should with the software.

    there is developer responsibility to be sure, but a driver issue is a driver issue ... game devs can't shoulder that burden.
  • JonnyDough - Friday, November 21, 2008 - link

    Hence, MORE STANDARDS! Reply

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