I've recently started encountering this problem where my external screens will sometimes turn off and on repeatedly at different intervals. It ranges from every few minutes to multiple times in a minute. It's not always both screens at once.
Could it be EM interference from something nearby? If they're cheap cables, they're often highly susceptible to it (if I use (either of the two semi cheap) HDMI cables for my monitor rather than DVI, my screen flicks off for a second everytime the fridge in my room switches off.
I should mention that this is happening at the office. Iām surrounded by other computers and screens and this has only recently started happening. Iām using DP cables but I donāt know how ācheapā they are as they were given to me by the company I work for.
I'm going with @anon26187667. If you run your normal utils and they show the GPU's/heads(output) are "there" and "attached" then this is likely outside your system. (They show in your sys info anyhow.)
I've had the same issue where I bought 3 of the same cable and used them on the same GPU. They worked...for a while. Then some mornings I'd sit down, fire things up to find one screen wouldn't turn on. System GPU saw it, but the monitor swore no signal. Work for a while, flicker clicker flicker. OR the scarier version was waking up to red or green "fuzz" all over the screen. Change the cables, flicker, no signal, fuzz, all gone. scAmazon is known for their cheap crap cables and I'm sure a lot of those cables have made their ways to local shops too. Local shops desperate to improve profit margins over scAmazon and that know a small percent of clients will ever notice the difference.
If you have cables of "different makers/brands" mix and match. Try to use ones that look like they have ferrite. Ferrite can also be misleading as some cords use that to mask the crappy insulation but if the cords are thin and crap to begin with it might be your best worst option. Outside that tell the boss to toss you $20ish in petty cash (or whatever denomination might be enough in your country/region) and ask to run to the local store and pick up a cable or two.
Just installed it, will see if it changes anything.
Iām fairly sure itās not the cables as Iāve tried connecting the same two screens with the same cables to my MacBook and nothing flickers. The cables as well as the screens and computers were all bought directly from Dell so I doubt thatās where it comes from unfortunately.
Dell is notorious for peddling trash. Their displays are often good, that's about it.
If the cables work OK with the Apple then perhaps they are decent but it might also be GPU/driver timing not agreeing with them. Have you tried just running single external to see if it still happens? If it does have you tried restarting X? Not suggesting that as a fix just as a link in the chain. Single screen works, if restarting X makes it behave again...all data points that might suggest something can't handle both the screens or just X getting crappy over time possibly due to RAM...it is an IGP so shared system RAM might be the culprate. (cue 3 identical spider men pointing to each other)
I've been running only one external screen for a few hours now and it still happens intermittently. Restarting X doesn't change anything, neither does rebooting as flickering can happen as soon as the session is opened. I'm thinking maybe it's an issue with the graphics drivers and/or the configuration but I haven't found a way to reset only that configuration without resetting anything else.
Well this is good to know. Has there been any dmesg or log messages with errors when it starts? I've also been thinking have you tried another distro just as a control. I mean it's an Intel system using an Intel IGP, Clear Linux might be the definitive way to go. Now if it still happens running Clear then something things are Bootsie Collins level funky.
***I say dmesg but I've noted Garuda doesn't kick things out as I'm used to for hunting debug log so if someone else can chime in on where the definitive syslog/dmesg style stuff is in Arch that'd be great.
Iām not seeing any errors related to the displays in dmesg and there is nothing of importance in journalctl from what I see - though so far I havenāt had any flickersā¦
I feel like I'm at the edge of my usefulness as dmesg and jctl are pretty different for info gathering than I'm used to in Garuda. The one caveat to that might be tail -f on your .xsessionerrors and tail -f /var/log/Xorg.0.log with a couple terms (or multitail) and just watching. I am curious though as your symptoms are really similar to my cable debacle.
Well, I don't have an .xsession-errors file. I'm monitoring the Xorg log right now but I'm not seeing much even though it's flickering again. I love the look and feel of Garuda but I think I'm just going to move away from it as I've been having too many issues running it with this laptop.
I'll try to run it live from a USB drive when I get the chance. I'm pretty sure it'll run fine though, this laptop had Ubuntu on it before I installed Garuda and I had no issues with the displays.
Alright so I haven't yet had the opportunity to try Clear Linux yet, but I should add that something has apparently been going on for a while and I hadn't noticed. This is a video of a fully black image on my external display (wait for the zoom): IMG 0372 Wa GIF | Gfycat
As previously noted, it doesn't happen with my MacBook nor with the screen unplugged from the computer (when in standby and displaying menus etc.). I've already tried multiple different cables. Not sure what could cause something like that to happen.
It really looks like a "mild" version of what was happening to me with the duplicate cables. Interfering static on the line. It's really strange because everything kinda screams it's the cables but it can't be if you can change OS and all is fine. The Mac I can kinda rule out because maybe there is better electrical shielding on the board that keeps it stable where the Dell just has charge build up and the cables can't resist it. Of course the second part of that is debunked IF you can change OS on the DELL and the issue also vanishes which leans back to something in the driver timing.
This might be some A Grade grasping at straws but IF you have a decent UPS handy and the screens and laptop aren't already on it, can you toss them on and see if that cleans things up just to rule out line power issues?
Linux sometimes doesnāt handle sub-standard cabling as well as Windows. So I guess itās possible Apple hardware might not have issues in some cases as well.