UPDATE - Definitely a driver issue. Problem goes away when I uninstall nvidia drivers, comes back when I reinstall them.
I'm having a really strange hardware problem. I have a workstation with two displays, they're both identical V173 ACER monitors. The workstation has two graphics cards, identical GeForce 6200 cards. Both screens are connected through D-sub cables. However one screen is bright white, and the other is kind of a dull yellow.
I have controlled for the following factors:
1) I have tried a third screen on both cards and get the same problem, one will always appear yellow (even the one that was previous bright white).
2) I have reset both displays to factory defaults.
3) I have reset all display options in all control panels (the NVIDIA control panel and the windows display panel) to defaults.
4) I have tried different cables.
5) I have tried making different monitors primary and secondary.
6) I have tried another graphics card.
The only thing I know for sure is that whichever monitor is set to be the primary monitor will be the yellowish monitor. The other one will always be the bright white one.
Thoughts?
Well I had a theory about IRQ sharing, but you have identified it as a driver issue. I think it is likely that nVidia never expected someone to run dual PCI cards. They probably only account for PCI-Express + PCI or AGP + PCI.
LCD Displays usually have a "Color Adjust" for different settings of "Kelvin". In essence, it adjust the display in a way that causes different amounts of tint to occur. Your monitors are using two different settings, one of which is biased towards red.
Are you running any other monitor-related utilities? I have no idea what nVidia is shipping these days, but try right clicking on the desktop and looking through the nVidia monitor control panel - it might have different stuff than the real monitor control panel. Look especially for any sliders (I see a panel labeled 'Adjust Desktop Color Settings' on my single monitor system). That might be monitor specific, and be the source of your trouble.
Is it possible to try a different computer, or using a different OS (like a linux Live-CD)? This would help rule out some strange settings in the OS.
Install the latest drivers from the nVidia site, or the card manufacturer's site, if they have special drivers. Otherwise, use earlier and earlier versions of the drivers to see if any work.
If the issue still exists, contact support for the graphics card manufacturer. It may be a "minor" manufacturing defect that makes the card incorrectly interpret signals from the driver.