Dennis HilkLinux Fix LabDE

Graphics, GPU & Display

NVIDIA Xid 79: GPU has fallen off the bus

NVIDIA Xid 79 indicates lost GPU accessibility over PCIe; preserve link and power evidence before repeated resets or a driver-only conclusion.

Editorial source review: Start with the evidenceShare this guide
On this page
  1. Symptoms & scope
  2. Possible causes
  3. Diagnose safely
  4. Evidence-guided next steps
  5. References & review
  6. Related problems

Symptoms & scope

  • Display output or GPU work stops and nvidia-smi cannot use the device.
  • NVRM logs Xid 79 or explicitly reports that the GPU has fallen off the bus.

Relevant environment

NVIDIA GPUs driven by the NVIDIA kernel module; desktop, compute and passthrough systems can all lose PCIe accessibility.

Recognizable messages (synthetic examples)
NVRM: Xid (PCI:0000:01:00): 79, GPU has fallen off the bus.

Investigate PCIe, power and platform evidence; a restart may recover access but cannot identify the cause.

Possible causes

These are possible explanations, not a confirmed diagnosis. Several independent faults can coexist.

  • PCIe link instability, device power loss or platform firmware interactions are possible.
  • Driver and virtualization defects are also possible; Xid 79 identifies lost access rather than a unique failed component.

Diagnose safely

Run one command at a time in the relevant session. Read the explanation first. Uppercase placeholders need your own values; tools and privileges vary by distribution. These commands are displayed here and never executed by the website.

Check 1

Read kernel events, with administrator access if needed; inspect the boot containing the failure.

journalctl -b -k --no-pager --grep='NVRM|AER|PCIe Bus Error'

Interpret the result: Preceding uncorrected AER errors strengthen a PCIe-path investigation. Their absence does not prove a healthy link because logs may be incomplete.

Check 2

Replace 01:00.0 with the GPU address found in lspci. This reads PCI configuration; some detail needs administrator rights.

lspci -nnk -vv -s 01:00.0

Interpret the result: Compare link capability and current status. A device missing after the incident is stronger evidence than a slow negotiated link alone.

Evidence-guided next steps

Inspect the powered-down PCIe path

If logs suggest lost PCIe access, power down normally and inspect GPU seating, risers and manufacturer-specified power connectors. A supported direct-slot comparison can isolate an intermediary path.

Precautions: Disconnect mains power and follow hardware instructions; never reseat a live GPU or mix modular PSU cables from different supplies.

Recovery / rollback: Return to the documented original layout only after inspecting it; retain the safer stable path if a riser is implicated.

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Collect evidence before another full test

If physical checks do not explain the loss, record BIOS version, driver version, topology and the first Xid/AER messages for NVIDIA or the system vendor. Compare one supported driver or firmware change during maintenance.

Precautions: Do not use an in-session GPU reset on the display GPU or an active compute workload. Firmware flashing requires the vendor’s recovery procedure.

Recovery / rollback: Keep the previous driver package and supported boot entry; restore them if the comparison worsens behavior.

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References & review

This guide was prepared from primary project or distribution sources and reviewed on the date shown. This is an editorial source check, not evidence that a fix was reproduced on your hardware. Diagnostic log examples are synthetic fixtures. Version-dependent details must be checked against your installed release.