Dual Monitors on Windows OS
Posted by Larisa Bolli on 09 July 2009 08:10 AM
Historically, the issue with multiple monitors on Windows has to do with setting the default profile for each monitor.

The only sure solution is to have one video card per monitor.

What usually happens, with a dual-head video card, is that when you assign a profile to one monitor - that same profile gets assigned to the other monitor. When this happens, one monitor ends up with the wrong correction data loaded into the video card LookUp Table (LUT) and also any program (like Photoshop) that asks Windows what profile to use for a monitor, gets the wrong information for one of the monitors.

Microsoft and the video card vendors are reluctant to admit this is an issue.

Recent experience has shown that multi-head PCI-express cards often work correctly, where in the past their AGP and PCI brethren have not. Whether that has something to do with PCIe architecture, or just that the video card driver software for the newer cards is working differently, I am not sure. However even that is not 100% true, so it is still necessary to check the operation of a specific card to see whether it works or not.

For example, in testing nVIDIA cards - even of the PCIe variety, I have not seen one handle this correctly.

The basic test, which uses only the standard Windows "Displays" control panel is to go into the Advanced Settings for one monitor, associate and set a default profile. Then go into the Advanced Settings for the other monitor and see if that same profile shows up there or not.

Some users report getting around this issue by using the "Microsoft Color Control Applet" which is described and available here:

(Gregory, D.)