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Attempting fix Xorg horiz and vert sync limits

April 06, 2022 — BarryK

Forum discussion on this topic starts here:

Reading the posts, you will get to a fix. Pemasu commented out the "HorizSync    35-81" in /etc/X11/xorg.conf and X started OK.

Those horiz and vert limits were put in way back when we had cathode-ray-tube monitors. It constrained Xorg so it didn't try to run the monitor with some insane horiz and vert rates.

My /etc/X11/xorg.conf has this "Monitor" section:

Section "Monitor"
Identifier "Monitor0"
VendorName "Monitor Vendor"
ModelName "Monitor Model"
HorizSync 35-81
VertRefresh 59-76
#UseModes "Modes0" #monitor0usemodes
Option "PreferredMode" "1920x1080" #monitor0prefmode

Not sure if should just remove those two constraints, in case it causes a problem on old hardware.

As Feodor posted in a email, a monitor may work at 90Hz, so that 59-76 range is too low. However, the monitor will probably still work at 60Hz.

Well, pemasu had success with commenting out the "HorizSync" line, so maybe I will do that as default, and we shall see what happens. I could try increasing the range, say "HorizSync 35-135", nah, will give it a go that line commented-out.  

Tags: easy