New build: Monitor requires power-cycle, un-/re-plug to be recognized

the_jest · 2023-04-07 12:13:05

I'm in the process of building a new Arch machine, and I've been confounded by a problem with the monitors, which I have to acknowledge is a broader hardware problem, not Arch-related.

My existing machine has two 4k Dell monitors, connected via HDMI and DP; I will be using these for the new one as well. The new machine is using an Intel i7-13700 CPU, which has integrated graphics, on an Asus ROG B760-I motherboard. I might eventually get a graphics card, but I'm not sure; the machine isn't for gaming. (The mobo has only a single DP and a single HDMI port, so I need to use a mixed configuration to have two monitors.)

The entire time I've been building this, the DP monitor has never worked at all; I get a "No DP signal from your device" error. The HDMI monitor works under highly specific circumstances: At various points during the boot process, I need to turn the monitor off with its power switch, unplug the HDMI, replug the HDMI, and turn it on with its power switch. It took me an enormous amount of time to figure this out. I seem to have to do this in two stages during the boot: I have to hit DEL during boot, do the un-/re-plug dance to see the BIOS, manually select the boot drive, and then after Arch boots, the monitor once again loses the image, and I have to do the un-/re-plug thing again to get to the console. This appears to be entirely consistent; it _never_ goes straight to the BIOS without needing interference, and I seem unable to go straight through the boot process and then do this dance at the end (if I try to wait, the un-/re-plug thing doesn't work: I apparently _have to_ interrupt the boot to manually choose the boot drive; I don't know what's happening during this time). There are other times when the image also dies and I can't get it back by un-/re-plug; I have to reboot.

Meanwhile, if at any point I unplug the HDMI cable from the new machine and plug it into the old one, the image comes right on, consistently.

Currently, Arch _is_ installed, but I don't have a graphical environment yet; it's taken so long to figure out how to get here that the installation process has been painfully slow.

I am at my wit's end, and would be very grateful for any suggestions for getting the HDMI monitor to work consistently, and the DP monitor to work at all.

seth · 2023-04-07 13:45:18

Did you test the output(s) against some other (eg. 1080p) monitor?
Do the outputs work before the OS starts (UEFI/bootloader)?
Have you tried plugging only /one/ of the monitors?

You can force the kernel to consider an output to be enabled, but if the IGP and the output fudge the handshake, that won't help at all.
https://www.kernel.org/doc/Documentation/fb/modedb.rst

the_jest · 2023-04-07 13:52:31

seth wrote:

Did you test the output(s) against some other (eg. 1080p) monitor?

Yes, apart from the two monitors I normally use, I've tried it with a 4K television over HDMI, and an old 1080p monitor using an HDMI -> VGA adapter. Same thing.

Do the outputs work before the OS starts (UEFI/bootloader)?

No, that's part of the point (again, acknowledging that this isn't an Arch problem): I can't even get to the BIOS screen without doing the un-/re-plug thing.

Have you tried plugging only /one/ of the monitors?

Yes. The DP monitor has never worked, whether plugged in on its own, or together with the HDMI monitor. The behavior I've described for the HDMI monitor is the same whether or not the DP monitor is plugged in.

Wolfick · 2023-04-07 14:21:27

First, try resetting the CMOS. If that doesn't fix it, update/reinstall the bios.
This one is a pain but if it still occurs, install ventoy onto a USB and try installing a couple of different distros [Manjaro, Ubuntu, Pop OS etc]. I would usually recommend just loading the live versions to test, but you are having the issue before then.
If it is still happening after all of that, It is almost definitely a hardware issue with the GPU, Mobo, CPU or even the SSD, computers be computers.

Edit: Actually, if you have a gpu, or can get a cheap one for testing, you may be able to quickly isolate it to either the Mobo or iGPU

Last edited by Wolfick (2023-04-07 14:28:50)

the_jest · 2023-04-07 17:39:43

Wolfick wrote:

Edit: Actually, if you have a gpu, or can get a cheap one for testing, you may be able to quickly isolate it to either the Mobo or iGPU

OK, this is interesting, but I don't know what it means:

I did try this—I removed the GPU from the old machine, and put it into the new one. And, in fact, the HDMI monitor now works perfectly, consistently, every time. The DP monitor still doesn't work at all, so I'll spend some time to try to figure out of this is a problem with that monitor, or its cable.

But what does this mean? Let's assume that the DP monitor is its own problem. What does it tell me that the HDMI monitor needed all this power-cycling when plugged into the mobo? Do I know if it's a mobo problem or an iGPU problem? (It would suck having to rebuild the entire thing to replace either of them, of course.)

Thank you for suggesting this, I wouldn't have bothered otherwise.

seth · 2023-04-07 19:17:59

Since the UEFI/BIOS is a affected, it's not gonna be the i915 module and since 1080p is affected, it's unlikely some HW limitation either.

Wolfick wrote:

First, try resetting the CMOS. If that doesn't fix it, update/reinstall the bios.

is by far the best guess, but it could also be the plug/jack being loose (though then the juggling should not deterministically cure it) and "The DP monitor still doesn't work at all" doesn't inspire great confidence if that's not the case w/ the previous system?

The HDCP handshake is notoriously fragile, you're using the exact same cables on the good and the bad system?

the_jest · 2023-04-07 20:38:20

OK, I've done a bunch of further testing. This is getting tiring. The BIOS is up to date, and resetting the CMOS didn't have any effect in the iGPU functionality.

So, the current situation is that the integrated graphics has been flaky all along: the DP never worked, and the HDMI required a specific jiggling at specific times to work. With an old low-end GPU, things get more interesting: the (single) HDMI port works with both monitors, which I hadn't tested before. Neither DP port works, with either monitor, with two different cables.

seth wrote:

"The DP monitor still doesn't work at all" doesn't inspire great confidence if that's not the case w/ the previous system?

In fact, while the DP monitor (i.e., the monitor that was connected via DP: as said, it does work with HDMI) did work with the old system, it was always somewhat flaky, and when I started the build process for the new computer (which originally involved moving old-system things around a bit), the DP monitor stopped working. So, in fact, it has been a while since I've had working DP.

But I still don't know what to make of this. Let's say I'm willing to forgo integrated graphics. What can I conclude about the lack of DP success? If the GPU had only one DP port, I could probably assume that there's something wrong with the port. But it has two DP ports, and neither of them work. Is it plausible that DP as a connection type doesn't work on this card? Do cards break this way? If so, I'd be willing to buy a new low-end GPU to fix the situation. I'm not sure what else to try; I don't have another DP device to test with.

Thank you for sticking with this.

the_jest · 2023-04-07 22:28:59

the_jest wrote:

But I still don't know what to make of this. Let's say I'm willing to forgo integrated graphics. What can I conclude about the lack of DP success? If the GPU had only one DP port, I could probably assume that there's something wrong with the port. But it has two DP ports, and neither of them work. Is it plausible that DP as a connection type doesn't work on this card? Do cards break this way? If so, I'd be willing to buy a new low-end GPU to fix the situation. I'm not sure what else to try; I don't have another DP device to test with.

Of course, it only just occurred to me that another obvious explanation would be that it's the DP port in that one monitor that's the problem. Unfortunately I'm away from it for now, but I'll try to use DP with the other monitor, which should reveal something useful.

Arch Linux

#1 2023-04-07 12:13:05

New build: Monitor requires power-cycle, un-/re-plug to be recognized

#2 2023-04-07 13:45:18

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#3 2023-04-07 13:52:31

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#4 2023-04-07 14:21:27

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#5 2023-04-07 17:39:43

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#6 2023-04-07 19:17:59

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#7 2023-04-07 20:38:20

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

#8 2023-04-07 22:28:59

Re: New build: Monitor requires power-cycle, un-/re-plug to be recognized

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