tl;dr version: weird video artefacts when using mplayer/vlc with GL driver, not with xv driver, but who accepts tearing in 2020...
System:
Motherboard: Socket AM4 Gigabyte AB350N-Gaming-Wifi, latest BIOS w/ latest Agesa, 32GB RAM
CPU: AMD Ryzen APU 2400G
Silverstone thin case
Noctua low profile HSF combo
Full HD Monitor with HDMI to DVI converter or DP to DVI converter, 720p Sanyo PLV-Z4 HDMI to HDMI connection
OS: Mageia, quite updated, kernel 5.7.19-desktop-3.mga7
Story:
This system was used as a headless server for almost 3 years (my remote desktop in a vnc session, music playback desktop in another vnc session with mpd for local music plus internet radio, plus cantata plus optionally firefox with youtube, fileserver, backup to remote file server, ...), now it's additionally used for the home cinema.
It had been running with 250 days uptime, no problems. (When I just built it, it had max uptime of several hours. After the second BIOS update, it got uptimes of several days, running without any graphics; it was only after the third or fourth BIOS update where it would run stable, by then it was rock solid. I never used the graphics though.)
After moving it to the other corner, there were some issues to get it to talk to the projector, it wouldn't always get the EDID info, I swapped monitors/connections, ctrl-alt-Fn for cli, ctrl-alt-backspace to restart the X server, etc.
I learnt a lot more than I wanted to know about pulseaudio and systemd in the process, plus bluetooth sink to play from smartphones,...
Playing video, there is a slight tearing effect, which can only be clearly discerned in scenes with strong contrast plus movement.
I use mplayer, so I checked and found it used the xv driver for video.
On the system where the projector used to be connected, I found it had always been using the gl driver. No tearing, no artefacts, fault-free so to speak.
That one works fine for video playback without any tearing, but with time (minutes, not seconds, also not hours), it will develop hideous artefacts.
I went through the various drivers, xv, gl, gl nomanyglyphs/nomanyfmts, x11, xshm, vdpau (installed the extra driver for that one), except for the xv driver all have weird artefacts to a greater or lesser degree.
Artefacts: outside the video window, the text on the Konsole may be garbled, there's all kinds of messed up stuff on GUI parts of VLC, etc.
The xv driver is okay except for the tearing effects.
The gl driver has the least problematic artefacts, but is unusable all the same.
Please see these images:
"Slight" artefacts, horizontal stripes:
Huge artefacts and mess, upside down parts:
Since I can grab the effects in screenshots, it's clear that it's not due to the cable connection.
Another thing: hplip had 2 cores (out of 8 logical cores) pegged at 100% for hours, and the cpu temp monitor was close to/around 100°C.
I found at the next boot that the fan had also stopped, no idea how long it had been dysfunctional...
(I never got the fan speed readout to work with lm-sensors, do get the temps...)
I deinstalled hplip, have no HP printers, don't know why that was installed...
So the questions are:
anything else I can try? Has anyone else experienced this type of issues?
I installed the extra VDPAU drivers, are there other drivers that may be worthwhile? Other settings?
Though I think it's safe to rule out the cable connection, could it be a buffer in the chipset?
If it's hardware related, I'm wondering if my APU is borked or if is the motherboard...