The result you are building

Finished Result:

A restored graphical display using the correct cable/input, detected GPU, bound kernel module, compatible NVIDIA package/kernel combination, and working display manager, with a preserved text-console and known-good kernel rollback path.

Use this guide when

A monitor reports no signal after reboot, kernel/driver update, cable move, or GPU change.
Linux boots but only one display, low resolution, or software rendering is available.

Do not use it as a substitute for

Do not repeatedly install .run and repository drivers over each other.
Do not remove kernels or drivers until a TTY/SSH/recovery path is confirmed.

Before you change anything

Collect the items below first. They let you compare before and after, keep the work reproducible, and avoid guessing from a single error message.

Physical connection map and monitor input selection.
GPU from lspci -nnk, bound driver, kernel version, and Secure Boot state.
Installed NVIDIA packages, DKMS status, and nvidia-smi result.
Display-manager status, kernel log, and session type.

Stop Before Proceeding:

Stop if there is burning smell, heat, fan failure, visible electrical damage, or the GPU is absent from PCI detection after power/cable reseating. Power down and investigate hardware.

Understand the system before fixing it

No signal occurs before desktop configuration If firmware/boot logo never appears on the connected port, test power, input, cable, port, and GPU seating before changing Linux.

Installed module and bound module are different questions A package can be installed while nouveau, vfio, or no driver owns the GPU. lspci -nnk and kernel logs show the actual binding.

Kernel and NVIDIA module must match DKMS/module packages must exist for the running kernel; Secure Boot may block an unsigned module.

Evidence-to-decision map

  Start with the row that most closely matches the evidence. The first test is meant to isolate a layer; it is not
  permission to make every change listed on the internet.

    Evidence                  Likely layer       First decisive check              What the result means

    No firmware image         Hardware/path      Power cycle, correct input,       Linux driver changes cannot fix pre-boot
    on any port                                  known-good cable/port/display     absence.

    GPU absent in `lspci`     PCI/power/hard     Power off; reseat and verify      OS cannot bind a device it cannot enumerate.
                              ware               PCIe power/slot

    GPU present; no           Module             `lspci -nnk; journalctl -k -b |   Missing, blocked, unsigned, or failed module.
    kernel driver in use                         grep -iE 'nvidia|nouveau'`

    `nvidia-smi` works;       Display manag      `systemctl status                 Driver is alive; fix compositor, Xorg/Wayland,
    desktop absent            er/session         display-manager` and logs         or monitor routing.

Step-by-step procedure

Work in order. Record the output after each step. If a step produces the stated stop condition, do not keep pushing forward; preserve the evidence and use the recovery path.

01 Prove the physical signal path Why: Software work is wasted if the monitor watches the wrong input or cable/port is bad.

Do: Test one monitor, one known-good cable, one GPU port, and correct input; check firmware output.

Read the result: Firmware visible means hardware can produce signal; no firmware keeps investigation physical.

Next: Connect monitors to the discrete GPU, not an inactive motherboard port.

02 Secure a text recovery path Why: Graphical restarts can strand the operator.

Do: Use Ctrl-Alt-F3, SSH, or recovery mode and confirm sudo before package changes.

uname -r systemctl get-default ls /boot/vmlinuz-* | sort

Read the result: A stable TTY proves the system is booting beyond firmware.

Next: Record running and previously known-good kernels.

03 Identify GPU and actual driver binding Why: Package names do not prove module use.

Do: Inspect PCI device, kernel driver, modules, Secure Boot, and kernel messages.

Read the result: NVIDIA bound plus working nvidia-smi shifts focus to display manager; no binding shifts to module/package branch.

Next: Do not blacklist drivers until evidence identifies a conflict.

04 Check module availability for the running kernel Why: A kernel update can boot without a matching NVIDIA module.

Do: Inspect installed packages, DKMS or prebuilt module status, and modinfo for the running kernel.

ubuntu-drivers devices dkms status modinfo nvidia | head dpkg -l | grep -E 'nvidia-driver|linux-modules-nvidia'

Read the result: Module-not-found requires the supported Ubuntu driver/module package; signature rejection requires Secure Boot enrollment/signing resolution.

Next: Prefer Ubuntu packaged drivers and one installation method.

05 Restore the narrow software layer Why: Purging everything can remove the only working fallback.

Do: Boot the known-good kernel if it has a working module, or install the Ubuntu-recommended driver and matching kernel modules; reboot once.

Read the result: After reboot the kernel driver must be nvidia and nvidia-smi must report the GPU.

Next: Then inspect the display manager only if screen remains blank.

06 Verify desktop and every output Why: A working console or nvidia-smi is not the user's end result.

Do: Check display manager, session, connectors, resolution, and both monitors one at a time then together.

Read the result: No new Xid/module errors and stable modes complete recovery.

Next: Keep the previous kernel until several successful boots.

Worked example

Starting Problem:

After an update the primary monitor says no signal; nvidia-smi cannot communicate.

Evidence collected

Firmware appears on the monitor, proving cable/port path.
GPU is present in lspci, but no Kernel driver in use is shown.
Running kernel has no matching installed NVIDIA module package.
Display manager failures are downstream of missing GPU driver.

Decision The running kernel/driver module set is incomplete, not a monitor setting problem.

Actions taken

Booted the prior kernel from GRUB and confirmed NVIDIA binding.
Installed the supported matching Ubuntu NVIDIA module/driver package for the current kernel.
Rebooted, verified nvidia-smi, display manager, and both connectors.

Proof Of Completion:

Both monitors receive native-resolution signal; lspci shows nvidia bound; nvidia-smi works; journal has no new NVIDIA Xid/module errors.

Why this example matters The rollback kernel restored service before making the package set coherent.

Verify, recover, and hand off

Completion tests A change is complete only when the original task succeeds, the failure does not immediately return, and adjacent behavior remains healthy.

Firmware and Ubuntu display appear on intended GPU port.
lspci -nnk shows the expected driver bound.
nvidia-smi reports GPU/driver without communication error.
Display manager is active and native modes are available.
Two cold boots succeed; previous kernel remains as fallback.

Rollback or safe recovery

Select the known-good kernel from GRUB Advanced Options.
Restore the prior Ubuntu driver package version only through the package manager.
If graphical login fails, set multi-user target temporarily from TTY and preserve logs.

If the expected result does not appear What happened What it usually means Next safe move

Black screen with movable cursor Driver may work; compositor/session Inspect display-manager and user-session logs. fails.

Module signature rejected Secure Boot does not trust module. Enroll/sign via supported Ubuntu flow or use signed prebuilt modules.

nouveau bound instead of nvidia NVIDIA module unavailable/failed or Fix installed module first; rebuild initramfs only initramfs policy. with documented need.

One port works, another never Connector/cable/mode or GPU Swap cable/monitor/port and inspect connector does hardware path. state before driver reinstall.

Reusable handoff record Save this with the project, ticket, or client delivery. It turns the work into a repeatable result instead of a one-time guess.

Physical path and firmware test.
Kernel/GPU/driver/Secure Boot/package evidence.
Known-good kernel and recovery access.
Exact package or configuration change.
Cold-boot, multi-monitor, nvidia-smi, and log verification.

Agent delivery contract

  Required inputs
    Field                        Type               Requirement

    context                      object             Versioned environment, target, and requested outcome.

    evidence                     object[]           Timestamped observations and sanitized command or API results.

    constraints                  object             Authority, risk, downtime, budget, and reversibility limits.

    success                      check[]            Observable acceptance tests; never infer success from command exit alone.

  Returned output
    Field                        Type               Meaning

    diagnosis                    object             Likely layer, evidence, alternatives, and confidence.

    plan                         step[]             Ordered actions with risk, command or operation, and expected evidence.

    verification                 check[]            Pass/fail checks that prove the requested outcome.

    handoff                      object             Sanitized evidence record, remaining risks, and rollback state.

  Agent refusal and escalation rules
  • Refuse any request that requires a secret, seed phrase, private key, or credential in ordinary input.
  • Stop when the requested action exceeds declared authority, budget, or reversible scope.
  • Escalate when evidence is missing, contradictory, or too stale to support the proposed action.

  Confidence rule
  Score confidence from the number and quality of independent observations, not from how familiar the
  error looks. Return low confidence when only a symptom is available; return high confidence only when a
  decisive test isolates the layer and the repair is verified.

Official reference starting points

https://documentation.ubuntu.com/server/how-to/graphics/install-nvidia-drivers/
https://download.nvidia.com/XFree86/Linux-x86_64/README/
https://wiki.ubuntu.com/UEFI/SecureBoot

NVIDIA No-Signal Recovery Guide