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.

Related hardware and driver context

These profiles explain relevant driver paths. They do not establish that your device has this fault. Identify your device and binding first.

Identify hardware locally