Nixos LiveCD works. Installed versions fail

Short: MSI Motherboard, AMD CPU, AMD GPU, precise details in appendix.
Boot off liveCD: fine. Boot off anything installed by livecd: no good.

So: I’d like to install with the same options/drivers/everything as the livecd - but with the one change of having a regular fliesystem in the end. How?

Details: Leaning towards “You have a hardware problem”, but I’d like to concretely nail that down before firing a parts cannon at it.

Nixos Gnome LiveCD (23 05 3037…) - I can boot the second option “nomodeset”. I get to a functional Gnome interface. I can run the installer to install on my nvme, sata, usb, ssd - all the installs seem to run without issues before rebooting.

But then: Booting off the fresh installs runs aground.

  1. Directly booting goes a ways, and then simply resets as if power cycled.
  2. Ok, on the “Nixos/Firmware” page, hit e, add “nomodeset”

Now it goes to a black screen … with a blinking cursor. That doesn’t move. I found a note saying basically ‘blind type this systemctl … startx’ sort of command, I’ve played with that and still gotten nowhere. ctrl-alt-del does drop immediately back to ‘logout logging’ before rebooting.

Back to booting off the nixos livecd, I ran a couple of online CPU stress test and GPU stress test sorts of things - trying to see if this is just “Overheat → reboot”. But. Running from the livecd, I have no problems on these tests.

I had Nixos 23 05 up and running on this exact hardware, until it simply shut off. (Thus: Suspect a hardware problem!) Nothing about the original install was very fancy: I did do “efiboot, OS1, OS2, home” as my partitioning scheme but I’d never even installed anything to the OS2 slot. Unfree checked & unchecked: no differences obvious.

Motherboard: MSI MAG B550 Tomahawk MAX WiFi
CPU: AMD Ryzen 9 5900X 12-core 24-Thread Unlocked
GPU: AISURIX (Radeon) RX 5500 XT 8gb GDDR6 Graphics Card
No recent changes, no smells of the magic smoke, no excess dust, shrugs.

I’m using this as 'learn and explore", or I’d have simply bought/scrounged a new graphics card by this point. But I have piles of questions.

  1. Ok, so. “Run these tools to test”. htop, iotop, lm-sensors, and a github project “gpu-burn” recommended by LambdaLabs. How do I get all that working correctly on a liveCD Any other tests I can run from a working livecd that might point to the expected hardware problem?

  2. How do I get logs while running off livecd? Nomodeset works, but the default does not … Why? How can I get that log?

  3. How do I install “Exactly the same as livecd/nomodeset except on regular fs”

  4. The flashing non-cursor on a blank screen still puzzles me. It’s not “Console”, but it’s also not into a window manager. Blind typing “reboot” doesn’t.

  5. Who thought taking the VGA port off was a good idea?!? (Ok, ok. teasing here.)

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So if you want, all the configurations for livecd are in, you can maybe just import it in your config, like:

imports = [

But I don’t know what happens exactly to your filesystem, you might be able to just overwrite the one of the installation cd. If you prefer, you can also read the content of that file and selectively copy/paste or import the configuration. To enable nomodeset:

boot.kernelParams = [ "nomodeset" ];

Regarding your issue, seems indeed to be hardware-related. I once had a similar issue: the problem was that one of the two CPU core broke, and there were some kernel param that was allowing the OS to only use a single core to boot at boot, while by default it would them both and crash.

… If I just import the livecd directly, I’ll end up with loopfs/tempfs/ and all the other fs shenanigans, no?

But yes, I keep waffling between “CPU problem” and “GPU problem”, and I’d like to nail it down concretely.

It works well enough with “livecd + nomodeset” that it’s pointing at something about the driver/microcode choices somehow. But that’s puzzling too.

I can’t test things today, but I’ll read up on how to do installation differently.


Case 1: LiveCD Boot directly with default → Freezes on a splash screen w/ MB vendor logo + Nix snowflake logo - then eventually power cycles.

Case 2: LiveCD Boot w/nomodeset → Functional NixOS … with no persistent readwrite. No tests show up anything weird here. (Probably mostly because I don’t know enough.) :wink:

Case 3: Fresh NixOS install → power cycles endlessly. No alarming messages flash past.

Case 4: Fresh NixOS install w/“nomodeset” set in bootmgr. → Black screen with flashing underline. not a cursor, and typing “reboot” does nothing.

Case 5: Fresh NixOS install w/ “boot.kernelParams = [ “nomodeset” ];” grafted into its configuration.nix. Same as Case 1.

Thoroughly confused.

  1. Are there good tests I can run while booted from the livecd?

  2. I think “Case 5” isn’t done properly. Editing the FreshNixOS’s configuration.nix isn’t sufficient. How to do I do “nixos-rebuild switch” for a not the running NixOS? Reading nixos-rebuild’s wiki … I’m on the same machine, I don’t want to adjust the currently running NixOS at all, I don’t want to tinker with boot settings.