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I have two Nvidia GTX 580s and a GT 610. I use the 580s to do architectural renderings and I want to use my 610 for display, so my 580s arnt wasting processing power managing the display. Because of my motherboard layout, and because the 580s take up 2 slots, I have to have the 580s on PCIe slot 1 & 2 with the 610 on 4 (3 is covered by the second 580). There is no other physical configuration for the cards. I called my motherboard manufacturer, and there is no setting in the BIOS to set which PCI slot is my default display, nor is there a BIOS upgrade to do this.

So, my question is this: Is there a way to set this in Windows? Even if the screen is blank until windows loads and switches to my 610 for display, that's fine.

Thank you in advance for anyone who can help me :)

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I'm not sure I understand the context of the question exactly. If the cards are installed, they use roughly the same amount of power at idle regardless of whether or not there's a display on them (just showing your desktop or documents or whatever is essentially no different than idle.) Unless I'm mistaken, Nvidia cards don't have any kind of extra-low-power mode or anything. –  Shinrai Jul 23 '12 at 12:49
    
I think he OP is afraid that displaying the desktop will use a bit is 'GPU processing time' and that he wants to have all of that available for OpenCL or CUDA tasks. –  Hennes Jul 23 '12 at 13:39
    
Yes, exactly. I want my 580s to only be used by my rendering program, maximizing its power. Having my 610 for display also allows me to do other things on my computer at the same time, which as of now, I cannot, the display becomes very slow. –  Trevor Jul 30 '12 at 13:02
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1 Answer

If the cards are not in SLI, then they are treated as separate PCI-E devices.

Windows' behavior for video adapters plugged into PCIE (on a system without Nvidia Optimus or anything else to complicate matters) is the following:

  1. Every video adapter gets its GPU booted, which means that the kernel loads firmware into the GPU and initializes it. This, with the Nvidia device drivers, turns on the compute (OpenCL/DirectCompute/CUDA), OpenGL and Direct3D functionality of the card, and also initializes proper power management for each card. Note that cards in SLI are treated as one logical video adapter in Windows' opinion, but each card still gets booted.

  2. The video adapters are enumerated, starting from the first one detected (which should be the one in the first PCI-E slot), looking for an electrically connected display. The video adapters know which displays are connected and what resolutions are available because they have smart port detection, which means that when you plug in the monitor, the GPU knows.

  3. Windows uses the list of video adapters and corresponding monitors to determine where to allocate the primary window station (primary desktop). This "window station" is assigned to the lowest-numbered PCI-E adapter with one or more displays connected. If it has 0 displays, it is skipped.

If the 580s don't have any display connectors plugged into the back of them, then they still have their VGA controller initialized, but it's not actively being used for graphics rendering at all... it's just sitting there waiting for something to be plugged in. Meanwhile, a certain amount of the graphics infrastructure has to be loaded in order to allow for computing architectures (OpenCL, DirectCompute, etc).

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What happens is that while I am using my 580s for rendering, the top card is also handling the display. This causes my top 580 to not run at maximum performance for my rendering program (especially VRAM, because it has to store everything for the display in the cards VRAM. This can hinder what I can and cant do). Also, while rendering, my computer becomes unusable, as the card doing the display is being maxed out. If I have the 610 doing the display, I will be able to use my computer while I am rendering and fully maximize the power of my 580s for what I got them for. –  Trevor Jul 30 '12 at 12:59
    
Then you need to plug your monitor(s) into the 610. –  allquixotic Jul 30 '12 at 20:48
    
I tried this, but I get no display. I pluged it into the 610, then turned on the computer and just get a blank screen. –  Trevor Jul 31 '12 at 12:38
    
Strange. Check your BIOS settings to see if the BIOS will let you choose between different primary display devices. If not, you may have to change to a motherboard that has integrated graphics (I recommend an Intel Ivy Bridge processor/motherboard combination). They let you choose the integrated graphics as the primary display, so that you can truly dedicate your GPUs to compute. Your primary graphics coming from the processor won't be blazing fast, but that's what you have your discrete cards for. –  allquixotic Jul 31 '12 at 15:43
    
Unfortunetly, there is no option, and I talked to their tech support for an hour trying to figure it out. –  Trevor Aug 3 '12 at 23:09
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