Debian 12, problem with old systems and new monitors.

[CptKrf]

Hardware
Mac Pro (Trash Can) AMD
Mac Pro (CheeseGrater) (2) Nvidia
Homebuilt Rysen Tower No name video card

I am installing Debian Bookworm on all four. As always, it installed fine on one of the old Mac Pros. And is working fine.
I always install only an absolute minimum system (SSH server and basic utilities) then add what I want later.

On the other three, the CLI install went fine and worked. So does the install of XFCE4. But...

On command 'startx', the screen immediately goes black and the machine(s) are apparently locked up. I can't ssh into them or Cmd-Fx to another desktop.

Worked on it for a while, then tried the Trash Can in the place of the old Pro. Then the Asus/Rysen. Same problem. Swapped the video card between the two identical old Pros, and still no-go. However, the original Pro still worked, which I thought was strange. Then, when I put one of the non-working boxes in the place of the good one, it worked.

The problem. Either basic Debian or XFCE (or attached drivers) do not like a 4k monitor attached to an old video card. Which is probably true. When these cards were made, 4k was still way out on the horizon. So, I need to lock XFCE to 1080p.

Now, while I have backed off for a while to let the frustration of several hours drain away, I thought I might as well ask about it. I will gladly accept with thanks any "Hey, dummy, why didn't you just simply change the ________."

Anybody?

 

[Oldhabbits]

Then, when I put one of the non-working boxes in the place of the good one, it worked

So, the problem is NoT Debian, but on the account of your monitor !
Of course, an old videocard would never be able to drive an 4K screen, not even an Apple… You will need to lock your monitor to the capacity of your videocard, not the other way around. Or did I understood your problem wrong ?

Cheers,

Eddy

 

[CptKrf]

Yep. Exactly correct. Obviously a 2013 video card will not support 4k, and Debian is just trying to feed to what it sees to be plugged in, without concerning itself with the card. There is no locking in the monitor, so I have to tell Debian to stick to 1080p. Its a smart monitor, but not that smart. Although I might have one that is. About to start on it again.

Later...
An easy fix. Changed the commented out line in /etc/default/grub to GRUB_GFXMODE=1920X1080.

I learned long ago that when one is gaining frustration in troubleshooting, the break room is one of the best tools available for making progress. Backing away from an exasperating problem for an hour or so - or even the time of a cup of coffee - can often payout very well.

 

[Oldhabbits]

An easy fix. Changed the commented out line in /etc/default/grub to GRUB_GFXMODE=1920X1080.

Good find, well done !

Cheers,

Eddy

 

[kc1di]

Glad you found a solution

 

[Alexzee]

Yep. Exactly correct. Obviously a 2013 video card will not support 4k, and Debian is just trying to feed to what it sees to be plugged in, without concerning itself with the card. There is no locking in the monitor, so I have to tell Debian to stick to 1080p. Its a smart monitor, but not that smart. Although I might have one that is. About to start on it again.

Later...
An easy fix. Changed the commented out line in /etc/default/grub to GRUB_GFXMODE=1920X1080.

I learned long ago that when one is gaining frustration in troubleshooting, the break room is one of the best tools available for making progress. Backing away from an exasperating problem for an hour or so - or even the time of a cup of coffee - can often payout very well.

Changing the resolution in the /etc/default/grub to the new monitor I purchased 5 months ago worked for me too.
Before the new Gigabyte monitor I was using an old Vizio TV for the monitor.