6 Monitors

I was wondering if any has used 6 monitors on Fedora 37? I use 3 right now and was going to get 3 more but didn’t want to waste the money if it didn’t work.

I’m curious what display card, or are you thinking of adding a second display card?

If just one display card, would you need daisy chaining to support 6 monitors, or does it have 6 connectors?

I think I remember my 6 monitor testing on Ubuntu on my current Windows hardware and I think I got it to kind of working in a live image of Ubuntu. I might test again at some point on my current linux machine, whose graphics card I think is a step up from the one on my Windows machine.

Both those display cards have 4 connectors. Of my seven monitors in my work space (4 now on Windows and 3 now on linux) two support being non last on a DP daisy chain. I have one hdmi only monitor and 4 with a choice of connector including DP, but for DP can only be last (or alone as a special case of last).

It is quite hard for me to get the extra displays close enough to test 6 so it was just a short test when I did it. I remember more details of my windows testing than of my ubuntu testing.

In Windows, when daisy chaining was live I couldn’t get Windows to launch at all. I got six monitors working only by turning monitors on in what I empirically discovered was working sequence, after booting with just one monitor.

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Out of curiosity I googled, and there actually exist at least one card with 6 ports, W6800, capable of driving 6 monitors at 4k. The price? Better do not ask.
If you accept a lower resolution, there are more cards available but a hub is needed. In any case it is a quite unusual configuration, so you’re on your own in case of troubles.
With two or more cards there should be no problems.

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I tried and I could not get DP daisy chaining to work at all with this driver.

I tried a bunch of different things and tried many reboots (because it frequently hung the GUI such that even ctrl-alt-F3 failed).

With nothing different in setup, the results vary with each boot (which is common when things depend on the timing of multiple monitors auto selecting input by sensing signals). I can’t turn that feature off on ANY of these Acer monitors. When multiple inputs are live, the input selection can be used to pick one. But when no input is live, it always auto scans to find one, so it doesn’t respond immediately when the display card tries to establish the connection.
But the variation is just among levels of failure, no path to success.

With the first monitor in the daisy chain set to DP 1.1, (by boot randomness) I get either complete failure of the daisy chain, or hardware mirroring (software sees only the first and the second is a mirror of the first.

With the first monitor in the daisy chain set to DP 1.2, I randomly get
A) software sees only the first.
B) software sees neither
C) software sees both, but the second hasn’t reported its valid resolutions so the choice is some low res defaults, selecting any low res default gets nothing displayed, but the software thinks it is working (normally connected, that same low res would be ugly but working).

Without DP daisy chaining, I can’t test over 4 displays.

We haven’t heard from the OP in a while, so maybe this thread is dead anyway. But I was curious about what works.

Thanks for the input I will just stick with what I have, I really don’t want to go back to Windows.

I got some longer DP cables, so I have more flexibility in what I test.
So now I find that DP daisy chaining does work.
The rightmost two in that layout are daisy chain and working fine.

My current theory is that there is some flaw in my EB321HULC displays. They kind of work second in a DP daisy chain, but apparently not correctly (they don’t support being first).
Long ago, when I tested 6 monitors, two were smaller monitors that I since threw out. Back then I owned only two EB32HULC, now I have four and hoped to use 3 of those 4 for 6 monitor testing. The DP behavior part of the firmware menu on those 4 does not match the manual I downloaded from Acer, so there might be a way to fix their settings. But I doubt it.

So I don’t have the right monitors to test 6, but I expect 6 would work just fine on my Radeon 6650xt card (with 4 connectors) if 4 of the monitors correctly supported the MST protocol of DP 1.2

The Mars-Tech shown there is actually a Roku TV that only supports hdmi.
My card has 1 hdmi and 3 DP.
The oldest pair of my Acer monitors are the ones that apparently have correct DP 1.2, while the middle (by age, not shown here) pair and newest pair apparently don’t.

Edit: I did more testing. Sometimes (right sequence of steps, similar to on Windows and luck in timing) I get one of the EB321HULC monitors to work second in a daisy chain. I never got two at once. Most failed attempts lock up linux and need hard reboot.

Daisy chaining just the two K272HUL monitors is not perfect either. As with all the DP daisy chaining on Windows, it can’t come up that way on initial boot nor resume from sleep. I need to turn the daisy chained monitors on after Linux is up. It is more robust than Windows in that getting that wrong (with just the K272HUL monitors) does not hang anything in linux. The monitors just don’t show up on reboot and can be fixed at that point just by turning those two monitors off and back on again (where in Windows, once that mistake was made, I needed to hard boot while the monitors were off).