These instructions for installing an NVIDIA card to use with IMOD may be
helpful.  They were updated in September 2024 to apply to Red Hat 8.  The list
of steps assume that you have already installed Linux with xorg-X11 and its
associated drivers.  Most of the commands need to be run logged in as root or
prefixed with sudo.

Note that some people have good luck using system packages for the NVIDIA
drivers; that is not covered here.  In our experience, this luck usually runs
out and we have to revert to installing NVIDIA packages.

1. Go to the NVIDIA web site (http://www.nvidia.com) and go to the driver
download page.  Specify your card type and OS type and use Search to find the
latest stable release drivers.  Download the file, e.g.
NVIDIA-Linux-x86_64-340.76.run.  Notice links to the README file, which
you may need to consult.  After you have installed the drivers, this file is
in /usr/share/doc/NVIDIA_GLX-1.0.

3. Either ssh from another machine or switch the screen to console mode with
Ctrl-Alt-Fn, where Fn may be F1, F2, F3, etc  - one of these should bring back
the graphical login screen, but others should just have a login prompt.  If
you get a black screen, press Enter to see if that makes it show a prompt.
After logging in, bring the machine to runlevel 3 with:
   init 3

4. Go to the location where you have placed your NVIDIA install file and
run it as recommended in the instructions, e.g.
 sh ./NVIDIA-Linux-x86_64-340.76.run

Allow it to modify your xorg.conf for you. If the procedure fails, you will
need to research the problems with your version of Linux.

On Red Hat 8, installation can fail with the message
   "Nouveau kernel driver is currently in use by your system"
The steps for dealing with this are:

  a) Make a file /etc/modprobe.d/denylist.conf with the line
        options nouveau modeset=0

  b) Edit "/etc/default/grub" and add this to the GRUB_CMDLINE_LINUX:
    modprobe.blacklist=nouveau
     Then run
        grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg

  c) If you want to copy the initramfs to a backup file, start a bash shell if
    not running one and run
      mv /boot/initramfs-$(uname -r).img /boot/initramfs-$(uname -r)-nouveau.img
      dracut /boot/initramfs-$(uname -r).img $(uname -r)
    or if you don't care about a backup,
      dracut --force

  d) Reboot the system and try installing the drivers again

6a. If you are logged in to a screen in console mode, type startx and see what
happens. Success is indicated by a Gnome or KDE desktop.  Failure is a message
saying the X server cannot come up.  A frequent message is a complaint about
no/missing screens.  This really means that the nvidia driver could not start
for one reason or another. You can examine the start up process in detail by
looking in the file /var/log/Xorg.0.log.  Make sure that the number of bits
specified in the Display line matches up with one of the screens that is
declared in xorg.conf

6b. If you are are doing this over ssh, return to runlevel 5 with
   init 5
and assess whether X is running with 
   ps -ael | grep X
   ps -ael | grep gdm
both should show processes.  If not, consult /var/log/Xorg.0.log.

7. Log out of a session started with startx.  Return to runlevel 5 with
  init 5

8. You can check whether the nvidia module is loaded with 
  lsmod | grep nvidia
This should give a line starting with nvidia

9. Log in as a normal user.  Assuming IMOD is installed normally, run 3dmodv
on the file obj7.mod (available in 
http://bio3d.colorado.edu/ftp/benchmarks/obj7.mod):

   3dmodv obj7.mod

Start the model spinning by typing Enter and 8 on the numeric keypad.
After 5 seconds or more, type o to get an output of frames/second.
You should probably get close to 60 FPS.
If it is a lot slower than this, the
NVIDIA drivers and GL libraries may not be installed correctly.
Note: You should get much faster rates with this model if you run
nvidia-settings, select "OpenGL Settings", and turn off "Sync to VBlank",
which limits the frame rate to 60.  For a better assessment of performance,
use the larger model ivem2578.mod from the benchmarks directory.

10. Note that you may need to reinstall the NVIDIA drivers whenever either the
kernel or X is updated to a new version.  Lately in Red Hat 8, this has not
been necessary.  After the machine is rebooted and
fails to start X, you just need to log in and enter, e.g.,
sudo /sbin/init 3
sudo sh ./NVIDIA-Linux-x86_64-340.76.run -as
sudo /sbin/init 5