Tuesday, November 13, 2007

Widescreen resolutions & DVI

One of our helpdesk reps reported an odd problem trying to setup a local workstation with 2 widescreens - when running in DVI, he couldn't get the horizontal resolution any higher then 1280 even though the monitor is optimized for 1400x900.

We're all used to fiddling with video card drivers to resolve these types of issues, but this one was a bit different because it required a monitor driver (when was the last time you had to install one of those?).  Slight side note, but generally speaking you should install the monitor driver because it usually ships with an color profile for the monitor which helps with replicating color consistently.

Before I attempted to install the driver for our Acer 1916W's, I figured I'd take a look at the drivers INF file to see if there was anything of interest to help resolve this issue, and sure enough, there was.

[DEL_CURRENT_REG]
HKR,MODES
HKR,,MaxResolution

[1280]
HKR,,MaxResolution,,"1440,900"

[AL1916W.AddReg]
HKR,"MODES\1440,900",Mode1,,"30.0-82.0,56.0-76.0,+,+"

The interesting line of course is the one proceeding [AL1916W.AddReg].  HKR is an identifier for "relative root", which in the case of the Acer driver is HKLM\System\CurrentControlSet\Control\Class\{4D36E96E-E325-11CE-BFC1-08002BE10318}\XXXX\MODES (the GUID is found at the ClassGuid property of the INF file).  You can see that the INF is adding in the supported resolution to the Modes key, allowing us to choose the correct resolution now!

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