I have an NVIDIA 9800GTX video card running 2 of my monitors and I would like to run a third over them but run it from the onboard VGA slot. is there any way to do this either with Windows XP and/or Ubuntu?

The quick answer...Yes, it can be done. Under Windows, it should be just a matter of plugging it in and installing the needed drivers. With Linux, you'll need to reconfigure your xorg.conf to reflect the additional monitor and card.

So if in Bios I have the onboard video disabled I just need to turn it back on and install the drivers in windows and xconfig in Linux correct?

I can't guarantee that it will work flawlessly, but that's a good place to start. Enable the on-board card in the bios, reboot, and see if Windows/Linux detects it. If the on-board vid card is nvidia, it should go fairly smoothly. If it's Intel or ATI, you are likely to have some issues but with some work, you'll get it.

One complication depends on the BIOS, another on the drivers, but I'm sure you could get it all to work in Linux and probably in Windows.

1) Most BIOS's have only two choices for configuring on board video:
a) On-board is primary and add-on is secondary.
b) On-board is disabled and add-on is primary.
What you would usually want is: On-board is secondary and add-on is primary. Most BIOS's won't let you do that, so you must manage with choice (a).
I've seen one system where it's even worse. That BIOS only allows one interface enabled. You choose which, but never both. With difficulty I figured out how to get xorg.conf to use both video even though the BIOS only enabled one.

2) nVidia's default support for cooperating between two video interfaces assumes both are nVidia. So if your on-board video is also nVidia things are simpler. If it isn't, you may need to run some extra experiments just to determine what goes in the xorg.conf file to make it all work right in Linux. Editing xorg.conf is very powerful, so it CAN be made to work. In Windows you have less direct and less documented control over the way video works. After installing new drivers from the manufacturer of the onboard video and from nVidia, it might just work with no further effort. Or you might be left blundering around with no clear direction.

I looked and looked and looked but apparently my mobo which is an Nvidia ASUS will only allow either one or the other. thanks for the help though.


Only thing is that I find it kinda odd that a NVIDIA board would not allow the use of all the VGA slots whether they are via Vid Card or On board. could I just be miss interpreting something?

The onboard and the first PCIE slot prob share the same bus or something that's why the mobo manufacture will only allow one or the other to be on at the same time. Or it could be that they just never figured you would want to use both.


Look for a bios update it may be something that's been changed since you last updated.

What makes you believe that? (How is the BIOS option for selecting the video phrased?) What have you done to verify that after selecting the onboard video, the other card really isn't enabled?

The lspci command can be used to get some very useful info about such things. To get a basic idea of what your BIOS is really doing to you, I would make one selection in the BIOS, boot up Linux and save the output from lspci, then make the other selection, reboot and save the new output from lspci. If the diff between those two files doesn't tell you enough, you probably should post them so someone with more experience can interpret them.

BTW, other experts here might want to suggest other commands to get info to compare between the boot ups with the two different BIOS choices. When I was diagnosing similar BIOS issues myself, I was booting a liveCD all the way into GUI mode for each BIOS choice (using Knoppix and/or Mepis), so it was doing an entire automatic configure of the X system, so the xorg.conf and associated log file gave even better info than lspci.

I really don't believe that. I think the issue is programming, not physical.

There is a lot of legacy design in the rules for BIOS initialization of the display. Much of that design makes no reasonable allowance for a second display. The design of PCI and later interfaces does make clean provisions for multiple displays, but the initial handshaking between the motherboard BIOS and the display BIOS must proceed very differently for a secondary display than a primary.

Very likely the BIOS code associated with the on board display interface doesn't know how to be secondary (just primary or disabled). That can't be true of the PCI card. It's BIOS must know how to be either primary or secondary. Possibly the motherboard BIOS doesn't know how to tell a secondary display interface to initialize itself. But that is rare.

I can't recall details (didn't really even understand when I did it) but the nVidia drivers can be made to use a secondary display interface even if the BIOS never initialized it. When I did it, I needed to get lspci and xorg.conf info from the autodetect of the display interface when only the card was enabled. Then I used that info to hand edit the xorg.conf that was produced by autodetect when the onboard was selected by the BIOS.

Johnsfine
So what you are saying if I am understanding you correctly is that I should go ahead and set the video to onboard and the PCI which expects to be secondary to something. Will then allow the Video Card to act as the secondary if I chose to enable the onboard only correct?

Sort of yes: I think the best shot at making it all work will end up with the BIOS video set to onboard.

I don't know what you mean by that and I don't even know what *I* mean regarding the aspect of my instructions closest to that. When I did it myself, I blundered my way through after looking at all the info that I asked you to gather that you seem to be ignoring.

Maybe some other expert knows more, but to get that to work in a similar situation, I really did need to have the Mepis liveCD create an xorg.conf file with the card only enabled and save that and make it create an xorg.conf file with onboard only enabled, and get lspci output from both those states. Only then did I have enough info to hand edit an xorg.conf file to make the card work as secondary when the BIOS had enabled only the onboard.

My bios has the video setting and when you enter it brings up PCI-E, Onboard, and PCI options and you chose from those 3 options. I suppose I was thinking the option would be set up in a way that was Primary (choices) = onboard and secondary(list of choices) = PCI-E or something like that.

I have toyed with the set up and I have gotten the monitor in the onboard going but not the other 2. I will continue to mess with it until it works

Thanks for the help though

I doubt any BIOS would let you make selections that way. It wouldn't make sense.

The major thing you are selecting is which is the primary video. Everything else usually either doesn't need any selection or goes along for the ride.

I guess I misled you by the way I used "secondary". I don't know a correct term for a video interface that is neither primary nor disabled.

After the major choice of which interface is primary, the BIOS could give you a choice of whether some non primary interface is enabled or disabled, but typically they give you no choice, they just decide.
Most often if the onboard isn't primary it is disabled, but if the pci isn't primary it is still enabled. There are exceptions in either direction.

The best I recall seeing was a bios that had a question for whether the on board was enabled or not as well as a question for whether the onboard or the pci was primary. It blocked the contradictory choice and accepted any of the other three combinations. The pci was enabled regardless of either answer.