HDMI-connected dual monitors not working

Rocky Linux Help & Support
1

This is my first post, so apologies if I not followed the forum’s etiquette.

I am trying to switch to Rocky 9.4 from CentOS 7 on my ten-year-old server
with its twin identical monitors and a GeForce 750 graphics card, but have
failed.

Under CentOS, the monitors are connected via the server’s two HDMI ports to
each monitor’s DVI socket, and the dual display works fine. However, if I
boot with Rocky 9.4 from an external SSD, nothing appears on the monitors
after the boot has completed. I can only see a display and login if I
connect the server’s sole VGA port to one of the terminals, and nothing is
seen on the second monitor. Indeed xrandr --listactivemonitors only
regards that one VGA monitor is active, whereas under CentOS two HDMI
monitors are active.

First I tried installing the latest version of the Nvidia drivers, both
from Nvidia and from RPM Fusion, and the 470 version from RPM Fusion,
all without success in enabling both monitors. I wanted to try 390, as this
seems to be the version recommended for GTX 750 by Nvidia (although
nvidia-detect responds kmod-nvidia), but the install finds no match for
xorg-x11-drv-nvidia-390xx. This was after updating my system to
5.14.0-503.23.2.el9.x86_64. The window manager is MATE. There is no
secure boot.

Is there some configuration file that needs editing, or some command that
enables Rocky to recognise the HDMI-connected monitors? Is the HDMI->DVI
not supported by the newer Nvidia drivers or Rocky, and hence should I buy
a VGA splitter?

I fear that after lots of attempts I may have some hybrid set of nvidia
packages installed. What’s the recommended way to clear out the nvidia
packages, to start afresh?

Many thanks for any answers to my questions, or suggestions on how proceed.

2

I don’t think anybody provides this anymore, if you didn’t find it in rpmfusion, another place to search would be elrepo, but I’ve checked that as well, and they no longer have the nvidia driver for 390. It is recommended for that card now to just use the nouveau driver that comes with Linux. If that doesn’t work, you would have to try and use the rpm packages directly from NVidia for the 390 - assuming you can find them. I have a laptop which requires NVidia 470xx drivers, and newer drivers do not work for it. I also know that these will disappear at somepoint in the future, and will then also have to just use nouveau if I cannot find the 470xx ones when they are deprecated.

This page seems to suggest version 334 for your card: Driver Details | NVIDIA but then when I fill in all the details doing a manual search: Download The Latest Official GeForce Drivers I get results as below:

brave_screenshot_www.nvidia.com
brave_screenshot_www.nvidia.com619×603 25.9 KB

brave_screenshot_www.nvidia.com (1)
brave_screenshot_www.nvidia.com (1)823×786 91.8 KB

brave_screenshot_www.nvidia.com (2)
brave_screenshot_www.nvidia.com (2)831×689 89.4 KB

if those results are correct, then some variant of the 5xx drivers should work.

Unfortunately, old hardware stops being supported after a certain amount of time.

4

It should work with HDMI. I would be tempted though to remove the NVidia drivers you’ve installed so far, and just try the default nouveau driver and see what happens? If it works and performs enough for your needs with just the nouveau driver, maybe that would be enough? Sure, it may not have the full 3D performance like the Nvidia ones, but if it’s just normal PC usage it may be enough?

5

I agree that it should work, hence I wondered if there was some configuration needed.

Well I do occasionally make some 3-d rendering of scientific data, but I’ll see what happens if
I remove the NVidia drivers.

1 Like
6

The proprietary NVidia drivers should include documentation, both as README.txt and html pages. This is definitely true for RPM’s from NVidia’s CUDA repo and ELRepo.
(I did rpm -qda \*nvidia\* to seek such files.)

Docs in driver version 570.86.15 have:

Current NVIDIA GPUs

NVIDIA GPU product Device PCI ID VDPAU features
NVIDIA GeForce GTX 750 Ti 1380 E
NVIDIA GeForce GTX 750 1381 E
NVIDIA GeForce GTX 860M 1392 E
NVIDIA GeForce GPU 1392 1028 066A E
NVIDIA GeForce GTX 750 Ti 1392 1043 861E E
NVIDIA GeForce GTX 750 Ti 1392 1043 86D9 E
NVIDIA GeForce GTX 750 Ti 139B 1025 107A E
NVIDIA GeForce GTX 860M 139B 1028 06A3 E
NVIDIA GeForce GTX 960A 139B 103C 2B4C E
NVIDIA GeForce GTX 750Ti 139B 17AA 3649 E
NVIDIA GeForce GTX 960A 139B 17AA 36BF E
NVIDIA GeForce GTX 750 Ti 139B 19DA C248 E
NVIDIA GeForce GTX 750Ti 139B 1AFA 8A75 E
NVIDIA GeForce GTX 750 Ti 139D E

In other words, even the very latest NVidia drivers should support some “GeForce 750” chips.
Note though that NVidia’s CUDA repo has two driver 570 versions: open and dkms. The open does not support pre-Turing chips; only the “closed” dkms version does.

As a new/recent thing, the 570-dkms allows Wayland, which still has issues on NVidia. One might have to explicitly disable Wayland, unless MATE does that. (This might affect Nouveau behaviour too.)

I have had machines (HP/Dell?) with both older and recent NVidia (latest was Ada Lovelace), where Nouveau of the installer fails to use the discrete card, so the install had to use IGP (or VNC, etc). I’ve also had machines, where (either Nouveau or proprietary) cannot show any virtual consoles – even though the (X11) GUI is ok.

I usually dnf rm \*nvidia\*, and possibly dnf module reset nvidia-driver (if CUDA repo was used), and check:

/etc/kernel/cmdline
/etc/default/grub
/boot/loader/entries/*.conf

for what kernel cmdline-options linger therein.

1 Like