Felix Miata wrote:

> deloptes composed on 2018-05-15 20:43 (UTC+0200):
> 
>> I used till now DVI to connect the PC to the monitor. I recently bought a
>> digitus 4K HDMI switch 4x1 to be able to switch between 3 HDMI inputs.
> 
> What model is that switch?
> 

Felix, I wonder sometimes if you really read the posts. I said it
is "digitus 4K HDMI switch 4x1" - you ask what model.

>> However when I switched on the PC and X started, all was messed.
>> Default resolution was 1280x720 instead 1920x1080.
>> The display area is partially out of the monitor size, so that the panel
>> is not visible and lastly the quality of the image was really bad (like
>> insufficient frequency or sync or whatever)
> 
>> I switched back to the DVI cable and I am wondering if someone can point
>> me to the right direction.
> 
> IME, most manufacturers of HDMI switches are incapable of making them work
> correctly - unless they do NOT include and automatic switching mode.
> Apparently they think everyone who uses them turns HDMI devices off when
> not in use (selected as the output by the switch).
> 
> The only one I've ever encountered that works reliably has no automatic
> switching function and is a long ago discontinued model.
> 
> Other than returning the switch as "defective", I can only think to
> suggest two things:
> 
> 1-power off all HDMI sources except the one you wish selected, then cycle
> the power to the switch.
> 
> 2-manually configure Xorg using xorg.conf to exclude possible modes except
> 1920x1080. (Set PreferredMode, and set HorizSync and VertRefresh to narrow
> ranges that can only compute to the 1920x1080 mode published in the manual
> or provided by EDID when connected without the switch inline).

IMO I need to set the physical size in xorg.conf, but your comment reminds
me to check the EDID. I wonder if the monitor can talk to the PC at all

regards