Lower resolution on monitor after KVM hookup. Monitor switched from Acer to Unknown.

anonku · 02-04-2015, 02:20 PM

I have an Acer 19" monitor. It worked fine at the resolution that I wanted 1280 x 1024.
Then I hooked up a KVM switch to it and now it lists it as an Unknown Monitor and the max resolution is 1024 x 768.
I am somewhat new to Linux and was wondering if there is a way to make it recognize the monitor type or increase the resolution.

I do not think the KVM should limit the resolution?

VGA connectors being used.

Ubuntu 14.04, Radeon 5500/6500 series. Dual Display, Acer is the second display.

allend · 02-04-2015, 06:50 PM

It is likely that the KVM switch is stopping your monitor from being probed for EDID information.
I would try running without the KVM switch, and collect the output from 'xrandr -q --verbose'. This information can be used for creating a suitable modeline for your monitor. For further details, look under 'Adding undetected resolutions' here. https://wiki.ubuntu.com/X/Config/Resolution

jefro · 02-04-2015, 09:33 PM

Generally if you boot to the unused side of the KVM it sends a faux signal to the OS.

Could be a bad or cheap kvm.

Set linux as button one and then keep it on while booting/loading.