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My PC (Compaq Presario) has an onboard Intel 3100 which is pretty lame wbut would be useful for testing on, or a 3rd monitor. I've then got a nVidia PCIx card installed. I can't seem to find a way to turn both on at once... is it likely this is a BIOS limitation?

Running Windows 7.

The official page suggests I can't do this but I wondered if there is a way?

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On some systems it will work OK. –  user84069 Jun 1 '11 at 23:00
    
indeed, i have seen this done, but it didnt work for me on a similar system with a slightly differing motherboard. –  Sirex Jul 11 '11 at 14:26

4 Answers 4

up vote 15 down vote accepted

To flesh out Sathya's answer a bit: In most systems, the same PCIe lanes are used for both the IGP and the PCIe-x16 slot for the video card. So either the slot can be used or the IGP. This means you can't even put non-video card devices (e.g. RAID controllers) into the x16 slot without losing access to the IGP -- you'd still have to install a video card in a different slot!

Late Edit: It appears that on Sandy Bridge systems with an H67 (and probably Z68, when they launch) chipsets, it's possible to run both the onboard GPU and an add-on graphics card at the same time. Other 6-series (and later) chipsets may work as long as both the CPU & MB Chipset support Intel's Flexible Display Interface, a DisplayPort-based standard that gives the integrated GPU a direct connection to the onboard video connectors.

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Annoying but thanks for explaining why the limitation exists, at least I can reboot and toggle through BIOS fairly easily. –  John Feb 3 '11 at 14:34
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You say that "It appears" this is possible on Sandy Bridge systems. Do you have any documentation or reference that confirms this? Have you done it personally? I notice that this question was closed as a duplicate of this one, but it's clearly not... Your latest edit makes it appear that the answer is quite different in the case of Sandy Bridge. –  Cody Gray Jul 11 '11 at 10:49
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@Cody: I think the key is that the CPU & Chipset must support Intel's Flexible Display Interface in order to work alongside a discrete GPU. That's what gives the system a direct connection from the integrated GPU to the onboard video connectors instead of sharing PCIe lanes. I don't have direct experience myself though, so I can't give you a definitive answer. –  afrazier Jul 11 '11 at 13:11
    
What if you have 2 PCIe slots OR if the video card is a PCI card? –  Clay Nichols Jun 23 '13 at 17:36
    
@ClayNichols: It's going to depend on how they're connected to the chipset. In many systems, 2 PCIe x16 slots run in 8x+8x mode when both slots are occupied and both slots share lanes, so if the onboard GPU is also sharing those lanes, then my answer still stands. –  afrazier Jun 24 '13 at 12:57

Unfortunately, there's no way around this limitation - using an external card automatically turns off the IGP.

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Just for clarity, this is true for many, but not all motherboards. I have personally run both an AGP card and the onboard to support two monitors on an older system. I have also heard of systems which will permit running the onbaord alongside a PCIe based card, but I have not tested that or researched it extensively. –  TimothyAWiseman Jan 19 '12 at 16:50
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@TimothyAWiseman: AGP was a dedicated interface, and at the time northbridge integrated video was probably done via a PCI interface (especially with Intel chipsets). That would have greatly limited the possibility of resource contention. That's just a hunch though. Ultimately the answer varied from chipset to chipset. –  afrazier Mar 26 '12 at 12:34

Old thread, but I have a Dell Optiplex 390 w/Intel integrated 2000 and am able to select multiple displays in BIOS and run both integrated and graphics card. Always looking for other desktops that have this capability as I am a quad-monitor individual on a dual-monitor budget....

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I saw this done on YouTube. The guy pressed 'delete' while his machine was booting. When the bios came up he went to 'video controllers' and re-arranged the order of the bootable graphics He made IGP first then PCIe second instead of the default way of PCI being first. He explained that by doing it this way the MOBO couldn't disable the IGP and that they both would play. I tried to do it on my machine but I haven't been able to find the control in order to re-arrange it, so I just had to use two video cards for the four monitors.

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Please consider linking to the youtube video if you think it helpful. –  John O Jan 27 '13 at 9:26
    
Probably he is referring to this video => youtube.com/watch?v=N8nMShuSfgI –  billaraw Oct 27 '13 at 12:53

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