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multiple graphic cards on Windows 7

    Question

  • Hi,

    I wonder how Windows 7 handles multiple graphic card. Multiple monitors too, of course, but each monitor connected to a different video card, not to 2 ports of the same card.

    In XP, things were normal: each GPU was doing the rendering of the windows on the connected monitor. That was the smart way of doing it. When I tried Vista, it did suck real bad. The frame rate became extremely erratic. According to my contact at nVidia, Vista forces the all the rendering to happen on the same card, and sends the output to the other card after. That made the whole point of having multiple high end GPUs a waste.

    I tried Windows 7. Apparently, it suffers the same problem than Vista. However, I haven't found any documentation on it, so it is just assumptions I make, but based on what I see, it appears to be the case: it works just fine with one application running on one monitor, but starting a second application on a second monitor make it extremely jerky.

    Note, this as been tried on the same computer I tested windows XP on. Same affinity, same CPU, same GPU, same everything but different OS.  Also, I do not use SLI, just 3 independent GTX 280.

    So is my assumption correct? Is this really how Wndows 7 works as well? If so, what would be the behaviour of XP mode?

    Thanks.

    Friday, July 17, 2009 4:46 AM

All replies

  • Win7 32- and 64-bit have no problems with what I have: an ABIT IX48 GT3 motherboard, Intel Core 2 Quad Q9650 cpu and two each Radeon 4870 video cards with 1Gb DDR5 RAM each and two each Samsung SyncMaster 225bw monitors. The video cards have CrossFireX selected. No problems moving between the monitors.
    Friday, July 17, 2009 5:11 AM
  • Win7 32- and 64-bit have no problems with what I have: an ABIT IX48 GT3 motherboard, Intel Core 2 Quad Q9650 cpu and two each Radeon 4870 video cards with 1Gb DDR5 RAM each and two each Samsung SyncMaster 225bw monitors. The video cards have CrossFireX selected. No problems moving between the monitors.
    Friday, July 17, 2009 5:11 AM
  • Yeah, but What I described is not moving one window from one monitor to the next, but running 2 instances of an application on 2 different monitors. Maybe I need to mention it's 2 heavy 3D apps.
    Friday, July 17, 2009 5:15 AM
  • I installed 7 on my computer, and after that all my monitors wouldn't go past 59 herz, that in it self might not sound like the end of the world, but when you play Eve online, it won't let you do all the window mode resalutions, and when you start running 4 accounts, each on it's own monitor and then the game goes down to running 10-15 fps per account. I'm running with a ATI Saphire HD 4850 X2 that has 4 monitor outputs, and no matter what i tried i couldn't make my screens run 60 herz it would reset it back to 59 all the time. making it impossible for me to use windows 7.
    Sunday, July 19, 2009 9:35 AM
  • You know I am stumbling across this thread years after the fact ... but here's what I have discovered

    In Windows 7

    Not using crossfire or SLI ... Multiple graphics cards using the same driver will use each independent GPU for their monitor/display plugged into it. No monitor plugged into that card - no GPU usage (unless cards are bridged SLI/xfire). When using different cards different drivers... the primary display adapter will do all rendering for all displays, and pass this information along to the other graphics cards which in turn will then put it out to their respective display. So make sure you have your most powerful card occupying the role of primary display adapter. If you are using the later setup consisting of multiple drivers... I would recomend a high end card as primary and cheap low end cards that merely provide the correct connection port that you need (VGA DVI S-video HDMI Display port etc etc etc). Depending on your number of expansion slots, you could run dual SLI/Xfire in addition to other graphics cards and multiple drivers ... giving you all the horse power you need across as many displays as you need. If you wanted to leave the load for a given display on its connected GPU you have to use the same driver as the primary GPU.

    Eve online users ... Disable desktop composition under the compatibility tab in the EVE.EXE properties window... or change windows scheme to a non Aero scheme (basic scheme) when running multiple clients.

    • Proposed as answer by ZerosInfinite Tuesday, February 14, 2012 6:11 PM
    Tuesday, February 14, 2012 6:09 PM
  • Hi ZerosInfinite,

    Yes, it has been years since I asked this question, but it's still open: I haven't found a solution yet. 

    What you say is interesting, but it doesn't really fit with what I'm seeing. All my graphic cards are the same: GTX 580. They all use the same driver. So each GPU should do it's own render and everything should be smooth. But it's not, it's still very jerky, as if I was int the "everything rendered on one GPU" mode. Is there a way to check what mode is used?

    Thanks,

    Vincent

    Tuesday, February 14, 2012 6:25 PM