Article ID: 951573 - Last Review: April 29, 2008 - Revision: 1.1

A monitor that reports information to the operating system by using EDID version 1.3 or a later version may behave unpredictably in installations of Windows that support EDID version 1.1

A monitor that reports information to the operating system by using Extended Display Identification Data (EDID) 1.3 or a later version may behave unpredictably in the following Microsoft Windows operating systems:

Windows Vista
Windows Server 2008
Windows Server 2003
Windows XP

Note These operating systems support EDID 1.1.

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CAUSE

This problem may occur because of inconsistencies between EDID versions 1.1 and 1.3. Typically, version standards are defined in such a way as to be backward-compatible. However, in these two versions of EDID, certain bit values are defined as having different meanings from one version to the other. This difference between definitions can generate misinterpretations that may, in turn, cause unpredictable behavior.

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MORE INFORMATION

For example, assume that you have a monitor that supports a screen resolution of 1680 by 1050 pixels. This monitor has a Standard Timing Identification block at bytes 38 and 39 of the EDID, and this block uses the values 0xb3 and 0x0. In EDID 1.3, these values represent a screen resolution of 1680 by 1050 pixels.

Note EDDI 1.3 bases its interpretation of these values on the horizontal resolution parameter of a screen that has a 16:10 aspect ratio.

However, in EDID 1.1, the vertical and horizontal resolution parameters are defined as equal (representing a 1:1 aspect ratio). Therefore, the screen resolution is interpreted as 1680 by 1680 pixels.

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