NVIDIA HGX H100 8-GPU Board Error SXid 62: NVSwitch Port Link Training Abort
SXid 62 designates an NVLink physical layer (PHY) communication breakdown where high Cyclic Redundancy Check (CRC) error rates prevent link training or cause an active link to abort during link negotiation between a Hopper GPU and an NVSwitch.
Hardware Diagnostic Matrix
Spec Ref #918aa8b2Required Diagnostic Tools & Instrumentation
Multimeter Probing Targets & Circuit Tolerances
Bench Calibrated ±5%| Test Point / Circuit | Target Nominal Spec | Expected State | Fault Condition |
|---|---|---|---|
| Main Logic DC Bus | 3.3V / 5.0V DC (±0.1V) | Stable DC Potential | <2.9V (Brownout / Sag) |
| Thermistor / NTC Sensor | 10kΩ - 100kΩ @ 25°C | Smooth Thermal Curve | 0Ω (Short) or ∞ (Open) |
| Safety Ground / PE Continuity | < 0.5Ω Resistance | Solid Earth Bond | > 1.0Ω (Floating Chassis) |
Common Symptoms & Fault Manifestations
- GPU dropouts or NCCL failure with 'unhandled system error / broken pipe' during multi-GPU jobs
- dmesg and nvidia-smi log events reporting 'SXid 62: NVSwitch port link CRC error'
- Reduced NVLink topology bandwidth or total link degradation down from 900 GB/s per GPU
Root Causes & System Failure Modes
Interposer pin deformation or debris causing differential signal attenuation on NVLink high-speed 106 Gb/s PAM4 lanes
Sub-optimal thermal interface material (TIM) or torque imbalance on NVSwitch/SXM5 heat sinks leading to thermal de-tuning
Dirty or damaged high-density board-to-board mezzanine connectors between the HGX baseboard and SXM5 socket
High-Voltage & Mechanical Safety Isolation
Prior to opening access panels, disconnecting terminals, or probing wiring, perform complete lock-out / tag-out (LOTO). Disconnect all AC mains, DC string isolators, and lithium battery banks. Allow internal smoothing capacitors at least 3 to 5 minutes to dissipate stored residual energy below safe threshold (<30VDC).
Step-by-Step Diagnostic & Resolution Procedure
Safe Isolation & BMC Telemetry Dump
Halt all workload execution. Drain host node via cluster orchestrator. Execute 'nvidia-bug-report.sh' and extract fabric manager logs (/var/log/nvidia-nvswitch/). Power down host, disconnect dual redundant PSU mains, and observe 5-minute capacitor bleed-off.
Port Isolation via Software Diagnostics
Before physical tear-down, map the failing link using 'nvidia-smi nvlink -e' and 'nvsm dump health'. Identify the exact SXM5 GPU (0-7) and NVSwitch ASIC index (0-3) reporting excessive CRC symbols to target physical inspection.
Mechanical & Contact Surface Inspection
Remove server top cover and cold plate/heat sink assembly following reverse cross-pattern torque instructions. Inspect the SXM5 connector pins and high-speed NVLink pads under 20x magnification for debris, thermal paste bleed, or bent pins. Clean with 99.9% IPA and dry thoroughly.
Precision Reseating & Torque Specification Application
Reseat the suspect SXM5 GPU module or replace the mezzanine board if trace degradation is confirmed. Apply fresh phase-change TIM. Fasten captive spring screws using calibrated torque driver strictly following NVIDIA 4-stage torque pattern up to final specification (typically 0.98 Nm).
Recalibration & Bandwidth Verification
Re-engage power supplies. Start the host and verify Fabric Manager status: 'systemctl status nvidia-fabricmanager'. Run NVIDIA System Management field diagnostics: 'nvsm diagnostic run --quick' and execute NCCL all-reduce stress benchmark for 30 minutes to confirm zero CRC replay increments.
Hardware Reset & Fault Clear Sequence
Controller ProcedurePrevention & Routine Maintenance Guidelines
- Always adhere strictly to specified stage-by-stage torque sequences when servicing SXM5 and NVSwitch modules to prevent differential impedance mismatch.
- Maintain clean-room discipline during cold plate replacement to prevent conductive particulate deposition on high-speed PAM4 NVLink traces.
Frequently Asked Diagnostic Questions
What does error code SXid 62 indicate on NVIDIA HGX H100 8-GPU Board?
SXid 62 designates an NVLink physical layer (PHY) communication breakdown where high Cyclic Redundancy Check (CRC) error rates prevent link training or cause an active link to abort during link negotiation between a Hopper GPU and an NVSwitch. In engineering telemetry, it indicates nvswitch port link training abort requiring circuit verification.
What are the primary triggers causing error SXid 62?
Diagnostic bench telemetry isolates the following common root causes: Interposer pin deformation or debris causing differential signal attenuation on NVLink high-speed 106 Gb/s PAM4 lanes; Sub-optimal thermal interface material (TIM) or torque imbalance on NVSwitch/SXM5 heat sinks leading to thermal de-tuning; Dirty or damaged high-density board-to-board mezzanine connectors between the HGX baseboard and SXM5 socket.
How do I reset and clear NVIDIA error SXid 62?
Clear active chassis fabric errors via Baseboard Management Controller (BMC) web interface or run 'ipmitool raw 0x30 0x01' followed by resetting the NVLink Fabric service: 'sudo systemctl restart nvidia-fabricmanager'. If errors persist across cold reboot, perform an HGX baseboard firmware reflashing cycle. If the error status repeats immediately after clearing, discontinue clearing and test circuit continuity.
Can I safely resolve error SXid 62 without specialized shop tooling?
This fault is graded as Advanced difficulty with Critical severity. Standard diagnostics require an insulated digital multimeter and appropriate hand tools. Always observe high-voltage isolation procedures.