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HP T420 - Resolution defaults to 1152x864.

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HP T420

Hello everyone,


I'm currently facing an issue with my HP T420 thin client running ThinPro OS.


Basically, using the graphical user interface I am unable to change the resolution from 1152x864 to the desired 2560x1080.

When I select a different mode I get the option to test the selection; the 'new' resolution will be exactly the same as before.

I've tried doing this several times with different resolution modes with exactly the same results, so choosing 640x480 will also result in the active resolution remaining at 1152x864.


Using the following command in terminal does work and changes the screen to the desired resolution;

xrandr --output DVI-0 --mode 2560x1080

However, this only lasts untill the machine is rebooted after which it'll default back to 1152x864.


Things I've tried so far: (Not listing the methods mentioned above)

*Updating BIOS from version L42 v01.04 to L42 v01.06. (latest version available)

*Attempted setting resolution with different accounts; Root, local user, domain admin, domain user.

*Attempted adding the T420 to HPDM, this results into an 'unidentified machine' with no options other than wake-on-lan.

*Attempted adding a startup script to change the resolution. Script works, won't trigger on startup/login.

*Reset the device to factory defaults.

*Reinstalled the OS using the provided image.


Anyone got any more suggestions to try and get this to work properly?



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is the display device you want to use compatable with 2560x1080? if the specs for the display do not mention this resolution then that may be your issue. also what refresh rate are you selecting? anything over 60 will cause issues

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Thanks for the reply, DGroves.


The monitor in question is an LG 29WK500, it supports a resolution of up to 2560x1080 and it supports a refresh rate of 75Hz. In the ThinPro7 OS I am unable to select a refreshrate using the GUI. Using the terminal command;

xrandr -q

It shows that the 'defaulted' resolution is set to 1152x864 at 75Hz.


When setting the resolution using that command to 2560x1080 it sets the refresh rate to 60Hz. (75Hz is still displayed as an option). I've just attempted a reboot after setting the refresh rate to 75Hz as I've not tried that yet, unfortunately it still reverts to 1152x864 at 75Hz upon reboot.


In the meantime I've also attempted to boot the device using several other linux distros;

Debian, Ubuntu and Mint.

These do not revert the resolution to 1152x864 on reboot.


I've also just taken out the internal USB drive that contains the ThinPro OS on it and re-created it using HP's Recovery and Update utility.  No luck with the ThinPro7 nor the Zero Client 7 versions.

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