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Thursday, August 18, 2011

Fixing the Native Resolution problem - WindowsXP

I had a hard enough time getting my Intel on-board graphics card to display the right resolution with Ubuntu last month. The problem was that the native resolution of my monitor is 1440 x 900, and the graphics card supports higher and lower resolutions but not this particular mode. I figured it would be easier on Windows XP- especially given the fact that Intel provides drivers for Windows only. But after all on Windows...
The instructions I followed were the ones given by Aaron Brezenski on the Intel Forum. The instructions are pretty clear, but need some amount of time to understand. I had previously read this article ("Unable to use the native resolution") but it was at best a waste of time. The updated driver also proved useless.The info given by Aaron is pretty comprehensive but misses out a few details, which I am adding below.

The problem is caused by the native resolution of most new flat screen LCD monitors (Digital Flat Panels) not being in the usual aspect ratios of 4:3 or 5:4 or even 16:9. For example the LG Flatron W1934S has a native resolution of 1440 x 900. The monitor usually communicates all these details to the graphics card using EDID structures. However, by Intels own admission this process does not work at times, such as on my machine. The chipset is, by the way G33/31. To check whether the EDID info is being read properly, one can use the MonInfo tool from EnTech. If the EDID info is not being read then installing the monitor drivers will also be of no help. One must then force windows to use a resulution even though it thinks it may not be handled by the monitor. As usual this is done by adding the appropriate registry keys. The key to be changed is called TotalDTDCount. Unfortunately there are many keys with the same name so it is impossible to figure out which is in use. The best thing to do is to modify the driver as mentioned in Aaron's post. The line to be added for a monitor running 1440 x 900 progressive scan at 60Hz is:

HKR,, DTD_1,%REG_BINARY%, 9A,29,A0,D0,51,84,22,30,50,98,36,00,9A,00,11,00,00,1C,37,01        ;1440x900@60...Progressive
Formatting can be copied from the adjacent lines in the inf file.After the file has been changed, the driver cannot be installed till the existing driver is removed. When the 'patched' driver is installed the system prompts security warning, these may be ignored.

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